The southwest monsoon withdrew from Delhi on Thursday, leaving behind an overall rainfall deficit of 19%, the Indian Meteorological Department (IMD) said.
Withdrawal of the monsoon is declared when dry weather persists for five days followed by a reduction in moisture levels. Monsoon usually begins withdrawal from the extreme northwestern parts of India in September.
This year, it began withdrawing from parts of southwest Rajasthan and Kutch on September 20. Thereafter, withdrawal has been slow with parts of northwest India receiving heavy rainfall last week.
The onset of monsoon in the city was a few days after the ‘normal’ predicted date and also withdrew a few days after the ‘normal’ withdrawal date.
For Delhi, the ‘normal’ date of withdrawal of the monsoon is September 25, according to the IMD. This year monsoon hit Delhi on June 30, a little after the normal onset date of June 27.
This monsoon season, the Safdarjung Observatory, Delhi’s primary weather station which provides a marker for the city, recorded two heavy spells of rainfall – one at the start of the season when the monsoon hit the city, and a second spell last week close to its withdrawal.
The IMD considers rainfall data during the monsoon season from June 1 to September 30. Safdarjung has recorded 516.9 mm of rainfall this season, which is 19% short of the normal of 639.7 mm. In contrast, Safdarjung recorded a large excess in rainfall last monsoon – 1169.7 mm.
The distribution of rainfall has not been equitable over the season. While June and August saw large deficits in rainfall at Safdarjung, July and September have recorded an excess.
For the city as a whole, rainfall this season has been in the ‘normal’ range, having recorded 451.4 mm against a normal of 544 mm till September 29. There was a deficit in 2020, 2019 and 2017, while 2018 and 2016 recorded rainfall in the normal range.
Rainfall across the districts has also varied this season, with some parts of the city receiving more rainfall than others. The only district that has recorded an excess in rainfall this season is East Delhi, with an excess of 30%. The largest deficit in rainfall was seen in Northeast Delhi (55%) followed by West Delhi with a deficit of 48%.