With 42.8 mm of rain falling in December, Delhi records the wettest December in 27 years. Safdarjung, the city’s main meteorological observatory, recorded 30.2 mm of rain between 8:30 am and 5:30 pm on Friday alone, marking the highest December rainfall recorded in a single day in five years. During the same period, rainfall in other locations, such as Pusa, Delhi University, and Lodhi Road, ranged from 18.1 to 39 mm of rainfall.

An active western disturbance combined with easterly winds was blamed for the unseasonable rains, creating conditions for consistent rain and thunderstorms throughout the area. A yellow alert was issued for Saturday and the following days and warnings of heavy fog and poor visibility accompanied IMD predictions of further rain.

Unusual December Weather Patterns

Delhi records the wettest December rainfall in 27 years, with 71.8 mm, the highest since 1997. Historically, the most significant December rainfall totals were recorded at 77.2 mm in 1901, 69.5 mm in 1967, and 68.1 mm in 1936. The IMD described this year’s rainfall as “remarkable,” attributing it to the interplay of two meteorological systems.

Experts, such as Skymet Weather‘s Mahesh Palawat, cautioned about the rain’s aftereffects, which might include thick fog due to the high moisture content. Similar conditions are predicted by IMD warnings for Sunday and Monday, with limited visibility expected across the National Capital Region.

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Rain Brings Respite from Pollution

The sudden downpours temporarily reduced the levels of extreme air pollution in Delhi. By 8 p.m. on Friday, the city’s 24-hour average Air Quality Index (AQI) had improved from 353 (“very poor”) at 4 p.m. to 325. Strong northwesterly winds predicted for December 30 and 31 may improve the air quality even further, potentially bringing the AQI into the “moderate” category during the weekend.

The Commission for Air Quality Management (CAQM) canceled Stage 3 of the Graded Response Action Plan (GRAP) on Friday night in response to better conditions. This judgment allowed diesel freight carriers to meet certain requirements to re-enter the city, relaxed restrictions on specific vehicles, and reopened schools for younger children. Forecasts caution that air quality may deteriorate again in the early part of next week.

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