Spatial Analysis of Aridity during Grapevine Growth Stages in Extremadura (Southwest Spain)

Abstract

Aridity is a key determinant of agriculture worldwide due to rising temperatures, rainfall variability, and drought frequency and intensity, amongst other factors. The De Martonne aridity index is particularly useful to evaluate the spatial and temporal variations in aridity in agricultural regions for characterising the climate of these areas and evaluating their susceptibility to climate change. From the mean precipitation and maximum–minimum daily temperature values recorded at 108 weather stations over 32 years (1989–2020) in Extremadura (southwest Spain), spatial analysis of aridity was performed at different grapevine growth stages. The present study aimed to (1) determine the mean aridity conditions in Extremadura according to year and growth stage and (2) assess aridity in six grapevine-growing areas of Ribera del Guadiana de Extremadura (Spain) protected designation of origin (PDO). To visualise aridity patterns, maps were generated using a geographic information system and a multivariate regression geostatistical algorithm (ordinary kriging). The climate of Extremadura is primarily Mediterranean at the annual scale, and aridity widely varies from extremely humid at the dormancy stage to arid at the berry development and ripening stages. This variation shapes the conditions of the studied grapevine-growing region. Furthermore, large differences were noted amongst the sub-areas of the Rivera del Guadiana PDO at the initial and final grapevine growth stages, requiring differential crop management. In addition, analysis according to growth stage allowed us to identify the most vulnerable areas and periods to climate change and potential grapevine-growing areas highly suitable for this climate.

1. Introduction

Climate is a determinant of many sectors, ranging from the economic to social sectors. One of the sectors most affected by climate is the economy and, more specifically, the agricultural sector. The agricultural sector is highly sensitive to climate because climatic conditions determine crop distribution and viability. Therefore, crop sustainability largely depends on climate [1]. Climate change has altered the optimal conditions for crops worldwide [2]. Therefore, the association between climate and agriculture has been and remains the subject of numerous studies (e.g., [1,2,3,4]).

Mediterranean Spain is characterised by a high spatial and temporal heterogeneity of water resources, and numerous areas are affected by water scarcity and frequent droughts [5].

The effects of climate change on the wine sector have raised great concern because both wine growing and production are sensitive to climate. The physiological behaviour of grapevines, as well as the ripening and organoleptic characteristics of berries, are strongly affected by temperature [6,7,8]. Meanwhile, the effect of precipitation on grapevines depends on the phenological stage. Although more precipitation is desirable during winter and at the beginning of the growing season [9], a lack of rainfall is conducive to ripening [10]. The effects of worsening water deficit and rising temperatures in Mediterranean vineyards have been extensively studied [11,12,13]. In addition to the season and cultivar, the climate of an area affects grapevine-growing operations [14,15]. The water deficit in the development phase of the berry causes a significant reduction in the weight of the berries, especially in periods of high temperature. However, during the maturation phase, this effect has not been found [16].

The effects of climate in southwest Spain must be explored, because Extremadura is the second autonomous community with the largest vineyard area (~83.763 ha) [17] in Spain and boasts, in addition to the Ribera del Guadiana protected designation of origin (PDO), two other protected geographical indications (PGIs) for wine, namely Cava de Denominación de Origen [designation-of-origin Cava] and Vino de la Tierra de Extremadura [Extremadura wine].

In Extremadura, approximately 80% of the total vineyard area is cultivated under arid conditions, without any water supply [18]; therefore, this region is highly vulnerable to increased temperature and decreased precipitation, as expected due to climate change. These changes may reduce grape and wine quality [19,20]. Climate change has been anticipated to reduce the suitability of warm and arid areas for grapevine cultivation [21]. Given the decrease in rainfall, particularly in the Mediterranean, irrigation is crucial to maintain wine production and quality [22]. This implies growing demand for water, which may be unsustainable due to the decreasing trend of precipitation in this area [23,24].

Aridity is a climate state, the average conditions of which in a region must be understood to identify the lack of moisture for the existing vegetation [25]. Aridity is the quotient between precipitation and temperature for a given period [26]. Aridity indices have been widely used to determine changes in climatic conditions and their effects on vegetation [25].

Numerous aridity indices have been used in the scientific literature, ranging from those based on evapotranspiration and precipitation, such as the Food and Agriculture Organisation (FAO) aridity index (e.g., [27,28]), to others based on temperature and precipitation, such as the De Martonne index (I_DM) and Pinna combinative index [29,30]. These indices are particularly valuable when applied to a specific crop. For grapevines, aridity indices have been used by Vyshkvarkova et al. [31] in Sevastopol, by Fraga et al. [13] in Portugal, by Tonietto and Carbonneau [32] globally, by Anderson et al. [33] in Australia, by Micah et al. [34] in Canada, and by Jones and Davis [10] in France. High or extreme aridity may be one of the key determinants of human activity [35]. Moreover, the spatiotemporal distribution of aridity has been studied in various European regions [24,29,36,37]. Ullah et al. [38] recommended using aridity in the indices at regional and local scales to obtain more robust results and formulate better planning, adaptation, and mitigation measures, thereby ensuring the sustainability of agriculture and water resources. It has been described that aridity in Extremadura is increasing in spring and summer [39]. This trend could influence the vine growing conditions in its different phases.

Due to the high interannual variability of the Mediterranean climate, aridity must be analysed according to crop stages in order to determine the most vulnerable stage and the possible impact on production and quality. The vine cycle is divided into different stages [40,41,42]. In Extremadura, the following stages have been described: vegetative growth, berry development, berry ripening, from the final stage to leaf fall, and from dormancy to new budding [43].

To this end, the main objective of the present study was to analyse the spatiotemporal patterns of aridity in Extremadura using I_DM at the different grapevine growth stages, focusing on the area of PDO and its subareas, as well as the current grapevine-growing regions. Our findings will allow for assessing the impact of climate change in different grapevine-growing areas of Extremadura in terms of aridity for informing the design and adoption of agronomic measures and agricultural policies aimed at mitigating these effects.

2. Materials and Methods

2.1. Study Area

The Extremadura region (37°57 to 40°29 N, 4°39 to 7°33 W) is located in southwest Spain, at the border with Portugal. This region is characterised by a rich diversity of ecosystems combined with topographic diversity across a territory spanning 41,633 km², with an average elevation of 425 m above sea level (m.a.s.l), as shown by the digital elevation model (DEM) (Figure 1). Extremadura is considered one of the most important ecological enclaves in Europe and displays a marked contrast between large agricultural and forest areas [44,45].

The climate of Extremadura is typically Mediterranean, characterised by interannual variations that affect both temperature and precipitation. The Atlantic influence, southern location, and low altitude in much of its territory favour moderate winter temperatures [46]. Typically, the monthly mean minimum temperature ranges from 3.3 °C to 4 °C in January and the maximum from 33.6 °C to 34.8 °C in July [47]. However, Extremadura is a landlocked region and, as such, shows a strong thermal amplitude, predominantly with dry and hot summers and maximum temperatures exceeding 40 °C [26,48].

The average monthly precipitation surpassed 600 mm in December and January from 1989 to 2020, with the average annual precipitation ranging from 380 to 700 mm in 84% of Extremadura; however, in the north, the average annual precipitation ranges from 710 to 1000 mm in Las Hurdes and Sierra de Gata counties, and may reach up to 1500 mm in the mountainous areas of Sierra de Gredos and La Vera. Extremadura has a dry season from June to September and a rainy season from October to May (accounting for 80% rainfall). Periodic droughts lasting two or more years are common, occurring every 8–9 years [49]. In addition, this region shows remarkable variability of microclimatic conditions due to its topographical diversity. Two large rivers (Tagus and Guadiana) cross Extremadura from the east to the west, and their drainage basins are located in the areas with the lowest altitude in the region. In 1999, Extremadura vineyards were recognised for their uniqueness, receiving the ‘Ribera del Guadiana’ PDO from the Spanish Ministry of Agriculture, Fisheries, and Food (Ministerio de Agricultura Pesca y Alimentación, MAPA) [50]. In total, six subareas have been established under this PDO.

2.2. Database

From daily maximum (Tx) and minimum (Tn) temperature and precipitation (Rr) data corresponding to the 1989–2020 period, provided by the State Meteorological Agency (Agencia Estatal de Meteorología, AEMET), recorded at 108 weather stations located in Extremadura and its surroundings (Figure 1), a homogeneous database was built. This homogeneity enabled us to complete the missing data. Our database passed the quality controls established by the World Meteorological Organisation [51]. From the initial data, the aridity index was calculated and incorporated into the database.

2.3. De Martonne Aridity Index (I_DM)

In the study carried out by Moral et al. [26], in which different indices were compared, in Extremadura, the I_DM was the index that best discriminated between both annual and seasonal climatic types in the region. In addition, Paltineanu et al. [52] found a strong correlation between the I_DM and the ETc over the entire growing season, and monthly values were also found for all crops studied, including the vine. Therefore, in the present study, I_DM was used, because this index yields reliable results in characterising the arid/humid conditions of a territory [26,35,53]. The I_DM was calculated using the following equation:

$$I_{DM}=\frac{P_a}{T_a+\mathbf{10}}$$

(1)

where P_a is the mean annual precipitation (in mm), and T_a is the mean annual temperature (in °C).

According to the I_DM values calculated using the equation above, the climate of a region can be classified, as outlined in

Table 1. Type of climate according to the De Martonne aridity index (I_DM, adapted after Baltas, 2007 [53]).

Classification	Values
Arid	IDM < 10
Semi-Arid	10 ≤ IDM < 20
Mediterranean	20 ≤ IDM < 24
Semi-humid	24 ≤ IDM < 28
Humid	28 ≤ IDM < 35
Very Humid	35 ≤ IDM ≤ 55
Extremely humid	IDM > 55

.

Moreover, I_DM can be calculated for a specific period. For a season, I_DM was calculated as follows:

$$I_{SDM}=\frac{4P_S}{T_S+\mathbf{10}}$$

(2)

where P_s and T_s are the precipitation volume and mean air temperature in the corresponding season, respectively.

For a specific month, I_DM was calculated as follows:

$$I_{mDM}=\frac{12P_m}{T_m+\mathbf{10}}$$

(3)

where P_m and T_m are the precipitation volume and mean air temperature in the corresponding month, respectively.

Furthermore, I_DM was calculated according to the grapevine growth phases (Figure 2).

2.4. Interpolation

A geostatistical algorithm has been used to model spatial variations of the I_DM. These spatial variations are described by a stochastic surface; that is, it is assumed that I_DM has values everywhere in the study area and they are considered random, taking a series of values according to a probability distribution.

Predictions obtained using a regression-kriging algorithm used in the present study separated the estimation into two components, namely a component for the trend and another for the residuals, which were subsequently summed. In other words, any climate variable, ${\mathrm{Z}}_{\mathrm{RK}}^{*}\left(\mathrm{x}\right)$—I_DM in the present study—at a point without data was estimated using regression-kriging, as follows:

$$Z_{RK}^{*}\left(x\right)=m\left(x\right)+r\left(x\right)$$

(4)

where $\mathrm{m}\left(\mathrm{x}\right)$is the adjusted trend derived using linear regression analysis, and r(x) is the residual, estimated using the ordinary kriging algorithm. Therefore, the predictive model can be presented as follows:

$$Z_{RK}^{*}\left(x\right)={{\displaystyle \sum }}_{j=0}^p c_j{v}_j\left(x\right)+{{\displaystyle \sum }}_{i=1}^n{w}_i\left(x\right)r\left(x_i\right), with v_0\left(x\right)=1$$

(5)

where ${\mathrm{c}}_{\mathrm{j}}$ is the coefficient of the estimated trend model, ${\mathrm{v}}_{\mathrm{j}}\left(\mathrm{x}\right)$is the jth predictor in $\mathrm{x}$, p is the number of predictors, and w_i(x) is the weight, determined by solving the ordinary kriging system for the residual r(x_i) at n sample points.

In the present study, elevation ($\mathrm{h}$) and latitude ($\mathrm{l}$) were used as predictors; therefore m(x) = a + b h(x) + cl(x) and, consequently,

$$Z_{RK}^{*}=a+bh\left(x\right)+c l\left(x\right)+{{\displaystyle \sum }}_{i=\mathbf{1}}^n{w}_i\left(x\right)r\left(x_i\right)$$

(6)

At each point, the residual r(x_i) was calculated as the difference between the land value and the estimate given by the trend; that is, r(x_i) = Z(x_i) − m(x_i).

Height was extracted from the Extremadura elevation model in raster format at a 1000 × 1000 resolution (Figure 1). Based on point data at weather stations, this model provides estimates for any other non-sampled place to generate a continuous surface covering the entire region. In the present case, the value of I_DM at any point in the Extremadura region was determined with a minimum resolution (pixel).

Finally, many digital models were generated for I_DM when grapevine growth stages were considered (Figure 2), focusing on the areas with PDO. The entire process, including the graphical representation of I_DM, was performed using ArcGIS v. 10.1. Geostatistical analysis was performed using the Geostatistical Analyst extension of ArcGIS.

3. Results and Discussion

3.1. I_DM in Extremadura According to Year and Growth Stage

The mean annual I_DM corresponded to the Mediterranean climate. The period of grapevine vegetative growth, which spans from budding to leaf fall, has been globally classified as semi-arid. However, during the dormancy period, once the leaves have fallen, aridity decreases, and the weather becomes extremely humid (

Table 2. Descriptive statistics of the De Martonne index in Extremadura for the annual, vegetative, and dormancy periods (1989–2020).

IDM	Mean	Classification	Max	Min	CV%	SD
IDM Annual	23.8	Mediterranean	55.4	12.4	33.4	8
IDM Vegetative	18.8	Semi-Arid	43.4	10.9	32.1	6.1
IDM Dormancy	46.9	Extremely humid	112	20.2	36.6	17.2

CV: Coefficient of variation; SD: Standard deviation.

). This classification is typical of a climate with sharp interannual contrasts, in addition to high coefficients of variation reflecting a high interannual variability. These two aspects highlight the strong grapevine resilience to these climates.

During the growing season, climate conditions widely ranged from highly arid to extremely humid phases (Figure 3). This season was initially humid, favouring the vegetative growth of buds and the formation of flower clusters. Subsequently, the climate became more arid at the berry development and ripening stages, enabling adequate ripening for quality production. However, the lack of soil water reserves may compromise both the quantity and quality of harvest, because rainfall is very low during these stages. Climate during the final growth phase, from harvest to leaf fall, is classified as Mediterranean, with plants accumulating reserves under average conditions; mild temperatures and slight rainfall during autumn. Finally, at the dormancy stage, once the leaves have fallen, aridity bottoms, and the climate is classified as extremely humid, which is essential for the creation of soil water reserves for the start of the subsequent crop cycle without water restrictions. These conditions are propitious for the advance and shortening of the berry development and ripening phases, as suggested by Webb et al. [54], Arrizabalaga-Arriazu et al. [55], Ramos [56], and Ramos and de Toda [57]. These average conditions indicate that grapevines are highly adapted to the Mediterranean climate [42] and to arid areas [58].

Our analysis of data variability revealed a large difference between the maxima and minima, with a high standard deviation at all crop stages, also exhibiting high spatial and interannual climate variability in Extremadura, as previously described by Moral et al. [26,59]. As a result of this variability, in some years, the crop stages displayed aridity indices far from their optimal values, which is expected to considerably affect vine growth and development due to very humid ripening stages, or very arid initial and dormancy stages (Figure 3).

3.2. Spatial Distribution of I_DM in Extremadura

Before producing the maps where the spatial distribution of IDM was displayed, the reliability of the kriged maps was assessed by means of cross-validation processes, estimating the variability of the predictions from the true values. Some prediction error statistics [60] were used as diagnostics (

Table 3. Statistic for validation of each I_DM map.

	Phases
Prediction Errors	Annual	Vegetative	Initial	B.Development	Ripening	Final	Dormancy
Root-Mean-Square	6.31	4.73	7.35	1.85	0.73	5.58	8.80
Mean Standardized	0.01	0.01	0.07	0.07	0.06	0.07	0.01
Root-Mean-Square-Standardized	0.91	0.90	0.91	0.99	0.93	0.94	1.07
Average Standard Error	7.05	5.32	8.06	1.76	0.77	5.93	8.98

): the root mean square error was between 0.72 and 8.80, which is around 20% of the mean value for each phase; the mean standard error was between 0.76 and 8.97; the mean standardized error was lower than 0.07; and the root mean squared standardized error was between 0.90 and 1.07. Since all these statistics were very low and the root mean square errors were close to the mean standard errors, the kriged maps were appropriate. Moreover, the assessment of uncertainty was completed with some additional information: since the mean standard errors were close to the root mean squared prediction errors and the root mean squared standardized errors were close to one, the variability in predictions was correctly assessed in all cases.

Spatial analysis of I_DM in Extremadura at the annual scale revealed five different aridity categories, albeit without extremely humid and arid categories (Figure 4). The predominant category was the Mediterranean (69.77% of the territory), followed by the semi-humid climate (23.33%). However, at the vegetative growth stage, the semi-arid category prevailed, covering almost 92% of the Extremadura territory and indicating limited water availability for plants during the growing season. In contrast, at the dormancy stage, the very humid category accounted for 96% of the Extremadura territory (Figure 4), when the plants no longer had a high water demand because the crop was dormant. These results indicate sharp climate contrasts.

During the initial growth stages, aridity widely varied in Extremadura across five categories, with the semi-humid climate prevailing in areas near the large drainage basins of Tajo and Guadiana (Figure 5), and accounting for 51.51% of the Extremadura territory.

In second place, humid areas (38.88%) were found at moderate altitudes (northeast and southeast Extremadura). The berry development and ripening stages showed an arid climate across virtually all of the Extremadura territory. The final stage was characterised as a transition to the dormancy stage and exhibited a pattern similar to the initial stage, with predominant semi-arid (65.8%) and Mediterranean climatic conditions.

3.3. I_DM in the Ribera del Guadiana PDO

I_DM analysis revealed that in 65.8% of the grapevine-growing areas in the Ribera del Guadiana PDO, the annual climate is classified as Mediterranean (

Table 4. Spatial classification (%) of the Ribera del Guadiana Protected Denomination of Origin, according to the IDM for the vine phases (1989–2020).

Phases	Arid	Semi-Arid	Mediterran	Semi-Humid	Humid	Very Humid
Annual	0	6.5	65.8	26.2	1.4	0
Vegetative Cycle	0	95.3	4.5	0.2	0	0
Initial	0	0	14.6	55.1	30.3	0
Berry Develop.	98.4	1.58	0	0	0	0
Ripening	100	0	0	0	0	0
Final	0	53.3	44.6	6.4	0.1	0
Dormancy	0	0	0	0	0	100

). At the different growth stages, the spatial distribution of climates was similar to that in Extremadura, except at the final stage, when the percentage of semi-arid areas (53.3%) of the Ribera del Guadiana PDO was lower than that in the entire Extremadura region (66%). Consequently, the percentage of areas with a Mediterranean climate was higher. These climatic conditions are more suitable for the accumulation of plant reserves, which occurs during this stage. These reserves are essential for the initial stage of the next crop year. In addition, these conditions favour the hardening of grapevine shoots, which is essential for the crop to withstand the rigours of winter.

3.4. I_DM in the Subareas of the Ribera del Guadiana PDO

At the annual scale, Cañamero and Matanegra showed the highest values of I_DM (Figure 6), and most of their territory was classified as semi-humid (57% and 76%, respectively) (

Table 5. Spatial classification of the subzones of the Ribera del Guadiana Protected Denomination of Origin (%) according to the I_DM for the vine phases (1989–2020).

Phases	Classification	Cañamero	Matanegra	Montánchez	Ribera Alta	Ribera Baja	Tierra de Barros
Annual	Semi-arid	0	0	0	2	36.3	0
	Mediterranean	26.5	23.8	70	85.6	63.7	60.5
	Semi-humid	57.3	76.2	27.6	12.4	0	39.4
	Humid	16.2	0	2.4	0	0	0
Vegetative	Semi-arid	38.5	52	79	95	100	75.3
	Mediterranean	55.3	48	21	5	0	24.7
	Semi-humid	6.2	0	0	0	0	0
Initial	Mediterranean	0	0	0	7.1	10.1	0.1
	Semi-humid	11.3	4.1	44.6	66.6	89	43.7
	Humid	69.4	95.9	51.9	26.2	0.9	56.2
	Very humid	19.3	0	3.6	0.1	0	0
Final	Semi-arid	18.6	11	56.2	81.4	99.7	52.6
	Mediterranean	69.5	89	42.9	18.6	0.3	47.4
	Semi-humid	11.8	0	1	0	0	0
	Humid	0.1	0	0	0	0	0

). In the other four areas, the Mediterranean climate prevailed (Table 5). Ribera Baja was the subarea with the largest percentage of the semi-arid category (over a third of its territory was classified in this category), which clearly limits the expansion of grapevine-growing areas. Most vines grown in this subarea are not located in the semi-arid area, as shown in Figure 5.

Overall, during the grapevine vegetative growth, the semi-arid climate prevailed, although Matanegra and Cañamero included large areas with a Mediterranean climate (55% and 48%, respectively), indicating favourable conditions for growing grapevines. Furthermore, at the dormancy stage, all subareas were classified as very humid, which implies average conditions favouring the accumulation of much-needed water reserves for the following vegetative growth cycle (Figure 6).

Aridity significantly varied at the initial growth stage of the crop (Figure 6). Subareas with the largest humid and very humid categories were, once again, Cañamero and Matanegra, followed by Montánchez, with a predominantly humid climate. Tierra de Barros and Ribera Alta showed similar distributions, with predominantly semi-humid and humid climates. Finally, Ribera Baja showed a predominantly semi-humid climate (Table 5). This variability across subareas shapes the type of viticulture and wine produced in these areas, because most of the grapevine leaf growth and development occurs at the initial stage, which is crucial for both wine production and quality.

Although no differences were noted between the berry development and ripening stages (Figure 6), the final growth stage (from harvest to leaf fall), once again, showed significant variability, as described for the entire region of Extremadura. The specific percentages for each subarea and their distribution are outlined in Table 5.

In summary, our analysis of subareas showed that, according to both year and growth stage, Matanegra and Cañamero have the largest surface areas with less arid and more suitable climate conditions for growing grapevines. In particular, lower aridity at the final growth stage during the accumulation of reserves may improve the composition, colour, and aroma of berries in these subareas [61]. Rivera Baja is the most arid subarea, whereas Montánchez, Rivera Alta, and Tierra de Barros are moderately arid. However, at the second and third growth stages, berry development and ripening, aridity conditions were comparable across all subareas due to high temperatures, which is evidently a hallmark of the PDO, denoting a highly peculiar viticulture, as described by Moral et al. [39]. The observed differences between the initial and final growth stages are expected to impact variety selection [62], cultivation techniques [58,63], and production quality [64].

3.5. I_DM in a Vineyard Area in Ribera del Guadiana PDO

At the initial growth stage, most of the vineyard area of the Ribera del Guadiana PDO presented semi-humid and humid climate conditions (

Table 6. Spatial classification in vineyard areas of the Ribera del Guadiana Protected Denomination of Origin (%) according to the I_DM for the vine phases (1989–2020).

Vineyard Area (%)	Initial Phase	Berry Development and Ripening Phases	Final Phase	Dormancy Phase
Arid	0.0	100	0	0
Semi-arid	0.0	0	81.4	0
Mediterranean	4.9	0	18.5	0
Semi-humid	67.5	0	0.1	0
Humid	26.9	0	0	0
Very humid	0.6	0	0	99.7
Extremely humid	0	0	0	0.3

), enabling adequate vegetative growth of the shoots. At the berry development and ripening stages, however, the entire area was classified as arid. From the final growth stage to leaf fall, 81.4% of the territory exhibited semi-arid conditions, whilst the remaining 18.5% exhibited Mediterranean climatic conditions, which are more favourable at this stage. Finally, during dormancy, 99.7% of the region was classified as very humid (Table 6).

These findings indicate strong dependence of grapevine growth stages on winter and spring rainfall, as well as the particularly limiting conditions in terms of high temperatures and low rainfall at the other stages of the crop cycle. This implies that the quality of the grapes can be very different depending on the place of cultivation. These conditions may lead to advances in berry ripening [65] and an imbalance of sugar composition and acidity, whilst reducing the anthocyanin content [66]. Therefore, such variations in aridity during the grapevine growth cycle characterises the unique viticulture of this PDO.

Although these conditions are conducive to quality viticulture, decreased aridity (due to lower temperatures) at the ripening stage is more favourable [67,68,69]. Overall, our climate analysis across different grapevine-growing areas showed that the climatic conditions may be improved at the initial and final stages, particularly in the Tierra de Barros and Rivera Alta subareas, by expanding grapevine growing to higher areas with lower aridity at these stages, as recommended by van Leeuwen et al. [58].

4. Conclusions

In Extremadura, the average annual aridity conditions for grapevine growing are Mediterranean, characterised by a sharp contrast between the vegetative growth (semi-arid) and dormancy (very humid) stages. This contrast characterises viticulture in Extremadura.

According to growth stage, the region shows variable territorial distribution and good climatic (semi-humid to humid) conditions at the initial stage; however, from the intermediate stages to harvest, the climate is predominantly arid, with intermediate (Mediterranean–semi-arid) conditions from harvest to leaf fall.

The six subareas of the PDO region present marked differences in climate between the initial and final growth stages. Matanegra, Cañamero, and Montánchez are clearly more humid, whereas Ribera Baja is more arid than the other subareas.

Most of the current grapevine-growing areas endure arid conditions ranging from semi-humid (budding–flowering) to arid (flowering–harvest) and Mediterranean (harvest–leaf fall). These conditions are propitious for an advance and shortening of the berry development and ripening phases and are conducive to grapevine growth and harvest quality; however, a rise in temperatures due to climate change at the ripening stage may decrease wine yield and quality.

At present, certain PDO areas that are not cultivated exhibit more favourable climate conditions at the initial and final growth stages than the current grapevine-growing areas, which may be a viable expansion strategy for coping with climate change and ensuring sustainable crop production. In the most arid areas, cultivation techniques must be adapted, such as the choice of more resistant varieties and rootstocks, changes in the management systems and orientation of the rows, the use of antiperspirants, and the use of controlled deficit irrigation.