Delhi’s southwest monsoon withdrew on September 23, two days earlier than normal, after delivering 16% more rainfall than the seasonal average, according to the India Meteorological Department (IMD). The withdrawal ended an 83-day monsoon season in the capital, which began five days later than usual this year.
The Safdarjung weather station recorded 728.6 millimetres of rain between June 1 and September 23, compared with the normal 629.7 millimetres for the period. The difference was 98.9 millimetres above the seasonal average. Despite the surplus, the IMD classifies the rainfall as being within the normal category under its assessment standards.
The normal date for the monsoon to reach Delhi is June 27. This year, it arrived on July 2. Its withdrawal date was also earlier than the normal September 25 schedule. The IMD said the monsoon had withdrawn from Delhi-NCR as well as Punjab, Haryana and Uttar Pradesh on Wednesday.
The early withdrawal is unusual in the context of recent records. According to information obtained from the weather department, the monsoon last withdrew from Delhi as early as September 20 in 2002. The current withdrawal is therefore the earliest in 24 years after that record, based on the dates cited in the report.
The immediate forecast for Delhi-NCR was for clear skies and no rain on September 24. The maximum temperature was expected to remain between 34 and 36 degrees Celsius, while the minimum temperature was forecast at 23 to 25 degrees Celsius. A cyclonic circulation was meanwhile present in the lower levels of the atmosphere over north-west Uttar Pradesh and adjoining areas.
The end of regular monsoon rainfall also brings attention to Delhi’s air quality. The city’s air quality index was recorded at 161, in the moderate category, on Wednesday evening, according to Central Pollution Control Board data. Reduced rainfall and moisture after the monsoon can allow pollution levels to rise, although the report does not provide a forecast of the extent or timing of any increase.
During the rainy season, Delhi’s air quality was largely recorded in the satisfactory or moderate categories. The average AQI for the first 30 days of July was 119, with 15 moderate days, 12 satisfactory days, two poor days and one good day. In August, the average AQI for the first 28 days was 92, including 19 satisfactory days and nine moderate days.
Air quality remained mostly satisfactory in September through September 23, with 19 satisfactory days and four moderate days recorded, according to the data cited. The next phase for the capital will therefore involve monitoring both the transition from monsoon conditions and the effect of drier weather on air quality, while the IMD’s withdrawal assessment marks the formal end of this year’s southwest monsoon season in Delhi.
