11 rainy days, rare fog: Why this was Delhi's coolest May in 37 years

NEW DELHI: Delhi experienced its coolest May in 36 years as the weather remained freakishly wet and pleasant through what is usually the hottest month of the year. At 36.8 degrees Celsius, the month's average maximum temperature was 3.1 degrees below normal, with 11 rainy days keeping temperatures below normal for as many as 22 days.
Only on four years have average maximum temperatures in May been lower in records since 1901. The last such year was 1987, when the mean maximum was 36 degrees C.
Even nights were unusually cool. The mean minimum temperature was recorded at 22.2 degrees C, 3.6 notches below normal and the lowest in at least 13 years. in readily available records since 2011.
The month saw 111mm of rain, against the normal of 29.4mm, making it the fourth wettest May since 1991.
Temps above 40 degree C on only nine days of May this year in Delhi
The temperature touched 40 degrees Celsius or more at Safdarjung on only nine days of May this year. By comparison, there were 19 such days in May last year and 24 in 2013. As a result, though some stations in Delhi saw heatwave conditions for three days, no heatwave day was recorded in May at Safdarjung, the city's base station.
"Five western disturbances (WDs) impacted the plains of northwest India this May, resulting in wet weather. The month usually sees two to three WDs affecting the region in May," said Kuldeep Srivastava, head of IMD's Regional Weather Forecasting Centre.
Of these five western disturbances, two impacted the first two weeks of May, the third in mid-May and remaining two around month-end. The even distribution of WDs through the month prevented the build-up of heat in the region that usually marks the month of May.
The met department's data shows that Safdarjung recorded the fourth wettest May since 1991 with rain excess of 262% as against the month's average of 30.7mm rainfall. May 2021, 2008 and 2002 logged 144.8, 165 and 129.3mm of rain, respectively, with 2008 being the wettest May on record.
The month started with the maximum temperature settling at 28.7 degrees Celsius on May 1. Temperatures remained below 40 degrees C for 21 straight days beginning April 20. It again dropped below 40 degrees Celsius on May 24 and has remained so since then. The city recorded the hottest day of the year on May 22 when the mercury hit 43.7 degrees Celsius aqt Safdarjung.
This May also saw fog, which is most uncommon for this time of the year. The visibility dropped to 100 metres at Palam on May 4 while moderate fog was recorded at some other locations of the city. Experts said the fog formed due to excessive moisture and calm winds. It was also the coldest May morning as the minimum temperature was recorded at 15.8 degrees Celsius. The last time Safdarjung saw a lower minimum temperature in May was on May 2, 1969, at 15.1 degrees Celsius.