For smaller areas like Delhi, 19% more or less than long-period average rainfall (50 years) is considered normal.
The monsoon withdrew from Delhi on Wednesday, with the city recording 20% less rainfall this season, the India Meteorological Department said.
The wind system had reached the national capital on June 25, two days earlier than normal, and stayed five days longer than usual. Normally, it withdraws from the city by September 25, Kuldeep Srivastava, the head of the regional forecasting center of the IMD, said.
“Change in the low-level wind pattern to north-westerlies, reduction in moisture content and cessation of rainfall indicates that the southwest monsoon has further withdrawn from some more parts of Rajasthan, remaining parts of Punjab, entire western Himalayan region, Haryana, Chandigarh, Delhi and some parts of Uttar Pradesh,” the IMD said.
According to MeT department data, the city recorded 20% less rainfall this monsoon season. For smaller areas like Delhi, 19% more or less than long-period average rainfall (50 years) is considered normal. Between minus 20% and minus 59% is deficient, and anything less than that is “scanty”.
“Therefore, the overall rainfall — which is an average of rainfall measured by all automatic weather stations and rain gauges installed at several places — falls in the deficient category this season, Mr. Srivastava said.
The Safdarjung Observatory, which provides representative figures for the city, recorded 576.5 mm rainfall against the normal of 648.9 mm during the entire season — a deficiency of 11%.
Earlier this year, the MeT department revised the date for the withdrawal of monsoon from Delhi from September 21 to September 25.
“The IMD revised the withdrawal date considering the trend in the last 20-25 years,” Mr. Srivastava said.