The National Centre of Meteorology (NCM) stated that May is considered one of the months of the first transition period (spring) between winter and summer.
”During this month the apparent movement of sun continue to move north of the equator where daytime gradually increases in the northern hemisphere which lead to a gradual increase of air temperature over most parts of the country during this month,” said the NCM in its May climate summary.
During this month, it noted, the effect of Siberian high pressure weakens while depressions affect the area from east and west and when it is associated by extension of westerly upper air troughs the amount of clouds increase with chances of rain.
Humidity decreases slightly during this month with compared to April especially during second half of the month. with chances of fog/mist formation particularly during first half of the month over scattered areas of the country while the frequency of occurrences of fog/Mist decrease during second half of May.
Climatic statistics:
Air temperature:
• Mean air temperature ranging between 30.6 and 33.6 ° C.
• Mean Maximum air temperature ranging between 37.3 and 40.7 ° C
• Mean Minimum air temperature ranging between 24.3 and 26.8 ° C.
• The highest temperature is 51.6 °C in Sweihan in 2025
• Lowest Minimum air temperature fell to 9.0 °c at Jabal Jais in 2005.
Wind:
• Mean wind speed 13 km/h.
• The highest winds of 117.2 (km / h) at Jabal Mebreh in 2010
Relative Humidity:
• Mean relative humidity 39%
• Mean maximum relative humidity ranging between 54 % to 82 %.
• Mean minimum relative humidity ranging between 14 % to 22 %.
Fog:
• In the 2021, May showed the highest frequency of fog with 4 occasions of fog and 10 misty days.
Rain
The highest amount of rain recorded during this month was 134.4 mm in Al Fali in 1981.
