Delhi's coolest May in 36 years: Copious rains lower average maximum temperature to 36.8°C

The India Meteorological Department (IMD) said on Wednesday (May 31)that Delhi this year witnessed its coolestMay in 36 years, with copious rainfall lowering the average maximum temperature to 36.8 degreeCelsius.According to Kuldeep Srivastava, the head of IMD's regional forecasting division, Delhi had an average high temperature of 36 degreeCelsius in May 1987.

"The average maximum temperature of 36.8 degreeCelsius in May this year is the lowest since then," he told PTI.

Only nine days in May had maximum temperatures exceeding 40 degreeCelsius, with heatwave conditions impacting some portions of the national capital for two days.

"The Safdarjung Observatory, which is representative of Delhi, has not recorded any heat wave in the pre-monsoon season this year. This has happened for the first time since 2014," Srivastava said.

Last year, the weather station recorded 13 heatwave days during the pre-monsoon season, nine in April and four in May. During this time period, there was just one heatwave day in 2021, four in 2020, and one in 2019.

A heatwave is declared when the highest temperature at a station is at least 40 degreeCelsius in the plains, 37 degrees in coastal areas, and 30 degrees in hilly areas, and the deviation from normal is at least 4.5 notches.

May, the warmest month in Delhi with a mean maximum temperature of 39.5 degreeCelsius, received 111 mm of rain, 262 per cent higher than the long-term average of 30.7 mm.

According to IMD records, this is also the fourth-greatest monthly rainfall after 165 mm in 2008, 144.8 mm in 2021, and 129.3 mm in 2002.

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The city received more than 20 mm of rain in April, the most in a single month since 2017, and saw heatwave conditions in localised areas.

What's causing the pre-monsoon showers?

Meteorologists blame the extra rainfall and below-normal temperatures this pre-monsoon season (March to May) to stronger-than-usual western disturbances, which originate in the Mediterranean area and send unseasonal rain to northwest India.

"Usually, five to six western disturbances are recorded in the northern plains in April and May. This time, we saw 10 western disturbances, mostly strong ones," said Srivastava.

"This is unusual. However, we cannot link it to climate change in the absence of data. There is no definite trend," he said.

Delhi recorded 184.3 mm of rainfall this pre-monsoon season (March to May) which is 186 per cent more than normal rainfall, according to the IMD.

(With inputs from agencies)

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