After the wettest May in over a century, here’s why Delhi may not follow the heavy rainfall trend in monsoon 2025

Delhi just had its wettest May in over 120 years, recording 185.9 mm of rainfall, including two heavy downpours, according to the India Meteorological Department (IMD). The previous record goes all the way back to 1901.

The IMD has predicted above-normal rainfall for the Delhi-Haryana-Chandigarh region this monsoon season. Experts say that Delhi typically sees two or three major rainy days during the monsoon, which often cause serious flooding.

Flashback: When monsoon brought Delhi to a standstill

When the southwest monsoon hit Delhi on 28 June last year, the city was drenched in extreme rainfall. Safdarjung station, the city’s main weather centre, reported 228.1 mm of rain in just one day. It was the highest single-day rainfall in June since 1936.

The downpour caused major disruptions across the city: waterlogging, traffic jams, trees uprooted, power cuts, and flight delays due to the collapse of a canopy at IGI Airport’s Terminal 1. Tragically, four people died.

Heavy rains didn’t stop there. In August 2024, Safdarjung logged two more days of intense rainfall, while July also saw strong showers in areas like the Ridge and Pitampura.

Rainfall trends over the years

TOI reports that IMD data from June to September shows that Delhi recorded seven heavy rain days in 2021, the highest in at least six decades. In comparison, the city saw two such days in 2023 and only one in 2022. Between 2018 and 2020, there were no heavy-rain days at all.

From 2011 to 2024, Delhi recorded only five very heavy and just one extremely heavy rain day, proving that such events remain rare.

What to expect this year?

While IMD hasn’t given a specific date for this year’s monsoon arrival in Delhi, it has confirmed that the region, including Haryana and Chandigarh, is expected to get more than 114% of the usual rainfall, officially considered “above normal.”

The usual monsoon arrival date for Delhi is 27 June. But this year, the monsoon is progressing faster than expected. It reached Kerala on 24 May (a week early) and Mumbai by 26 May (over two weeks early).

Last year, Delhi received 1,029.9 mm of rainfall, 62% above the long-period average (LPA) of 640.4 mm. In 2023 and 2022, the city received 660.8 mm and 516.9 mm respectively. The 2021 monsoon was the wettest since 1964, with Safdarjung logging a massive 1,176.4 mm.

How rainfall is measured

According to IMD:

• Very light rain: Trace to 2.4 mm in 24 hours
• Light rain: 2.5 mm to 15.5 mm
• Moderate rain: 15.6 mm to 64.4 mm
• Heavy rain: 64.5 mm to 115.5 mm
• Very heavy rain: 115.6 mm to 204.4 mm
• Extremely heavy rain: Above 204.5 mm

Pre-monsoon rain already high

Between 1 March and 30 May, Delhi received 103.8 mm of rain, nearly double the usual 55.5 mm. This placed the capital in the “large excess” category for pre-monsoon rainfall, with an overall surplus of 87%.

Inputs from TOI