Long-Term Fog Climatology, Operational Forecast Evaluation, and Meteorological Controls at King Fahd International Airport, Saudi Arabia

Fog is a major aviation hazard that reduces visibility and disrupts airport operations. This study presents the first integrated assessment of fog climatology, operational forecast evaluation, and meteorological controls at King Fahd International Airport, eastern Saudi Arabia, using METAR observations and Terminal Aerodrome Forecasts (TAFs) during 2001–2025. Fog variability, duration, intensity, and associated meteorological conditions were investigated, and TAF performance was evaluated against observed fog events. Fog occurred predominantly during autumn and winter, with the highest frequency in October, and reached a pronounced maximum near 0600 LT. Severe fog was the prevailing intensity type throughout most years. Although annual fog frequency exhibited slight decreasing trends, the annual longest fog duration increased marginally. TAFs successfully predicted only 49% of observed fog days during 2006–2025, highlighting the continuing difficulty of operational fog forecasting. Fog formation was favored by relatively high mean sea-level pressure (1010–1019 hPa), calm to low southerly winds (0–3 m/s), relative humidity of 87–100%, and dew point deficits of 0–2 °C, while wind speed exhibited the strongest statistical association with fog occurrence among the investigated meteorological variables. These findings provide a climatological reference and practical meteorological thresholds for improving aviation fog forecasting and airport operations in coastal arid environments.