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.

Fog is a low-visibility hazard in hyper-arid coastal environments. This study investigates the climatology, temporal variability, associated meteorological conditions, and predictability of fog at Yanbu International Airport, Saudi Arabia, using hourly METAR observations, Terminal Aerodrome Forecasts (TAFs) and ERA5 reanalysis during the period of 2005–2025. Fog showed seasonal and diurnal variability, with an autumn maximum in October and a peak around 0700 LT. Annual fog frequency and maximum duration exhibited interannual variability but no statistically significant long-term trends. Fog occurrence was associated with high relative humidity (≥94%), small dew point deficits (0–1 °C), and calm to light easterly winds (0–2 m/s), whereas mean sea level pressure (MSLP) played a secondary role. ERA5 vertical-profile analysis identified temperature inversions during 55.0% (94/171) of observed fog hours, indicating lower-atmospheric stability. ERA5 composites for 90 distinct fog events showed persistent moist conditions over the Red Sea and adjacent coastal region from −12 h through fog onset, with the strongest moisture availability and horizontal transport concentrated at 1000–975 hPa and progressively weaker signals at 950–925 hPa. TAF verification indicated limited forecast skill under the simplified daily-event framework. These findings establish a long-term climatological baseline and provide evidence of the thermodynamic and moisture conditions associated with fog formation in this hyper-arid coastal environment.