Delhi records wettest August in over a decade? Know what the IMD data says

From weeks of deficit to a surge of rain pushing August 2025 into the record books, the monsoon of Delhi has shifted dramatically this year. The national capital has had its second-highest August rainfall over a decade by late August. Across 11 rainy days, Delhi has witnessed 311.8 mm of rain in August, putting it just behind last year’s 390.3 mm in 17 days.

August rains reflected moderate variation between 2018 and 2021, followed by two very dry Augusts in 2022 with 41.6 mm of rain and 91.8 mm in 2023. However, the recovery in 2024 and 2025 quickly shifted from deficit to surplus by August, according to the India Meteorological Department.

As per the IMD, rainfall in Delhi rose exponentially this year, recording 553.8 mm of rain this season, 36 per cent above normal, remaining behind only Ladakh and Rajasthan. But surprisingly, Delhi witnessed rainfall season weak with only 56 per cent of rain, below normal in the week ending June 11. But, it received a slight 12 per cent surplus rain by June 18, and another 28 per cent deficit on June 25. However, July saw little improvement.

The turnaround came as rainfall rose 13 per cent above normal in the week ending July 30. Between June to July, the city witnessed only one week above normal rainfall. August, however, showed a sharp rise, 26% above normal in its first week, followed by 35% by August 12 and 37% by August 20. These heavy spells erased the earlier deficits, pushing Delhi into one of its wettest monsoons in more than a decade.

How AQI of Delhi shift with rain?

Generally, Rainfall comes with clean air for the city, but the August data shows a mixed picture. In 2020, with 237 mm of rain, the AQI of Delhi dropped to 64, among the cleanest in the recent past. Similarly, in August 2024, the wettest in over a decade at 390.3 mm of rain, the AQI improved to 72.

In contrast, dry spells kept pollution higher. In 2022 (41.6 mm rain) and 2023 (91.8 mm rain), AQI levels stayed elevated at 90+ and 116. This August, the AQI averaged around 91, an improvement over dry years, but not as clean as wetter ones.