Monsoon Showers Bring Relief to Delhi-NCR as Temperatures Drop Sharply

30 June, 2025

Delhi and the National Capital Region received light to moderate rainfall with thunderstorms on Monday morning, providing significant relief from the heat. The Safdarjung observatory recorded a minimum temperature of 24°C, nearly four degrees below the seasonal average. The rain also improved the city's air quality, pushing the AQI into the 'satisfactory' category. The India Meteorological Department has issued a 'yellow alert,' forecasting more showers and advising caution due to potential waterlogging in low-lying areas.

Unpacked:

What is a 'yellow alert' and what precautions should residents take during such weather warnings?

A 'yellow alert' from the India Meteorological Department signals potentially adverse weather, such as heavy rain or thunderstorms, but not extreme danger. Residents should stay informed, avoid low-lying or flood-prone areas, watch for waterlogging, and be cautious while commuting due to slippery roads or reduced visibility.

How does rainfall improve Delhi’s air quality, and how significant is this improvement usually?

Rainfall helps wash away dust, pollutants, and particulate matter from the atmosphere, leading to an immediate drop in air pollution levels. This often shifts Delhi’s Air Quality Index (AQI) from 'poor' or 'moderate' to 'satisfactory' or even better, though the improvement may be temporary if pollution sources persist after the rain stops.

How common is it for monsoon rains to be delayed or arrive late in Delhi?

Delayed monsoon arrivals are not rare in Delhi. For example, in 2021, the monsoon arrived as late as July 13. The onset varies year to year, typically between late June and early July, with occasional delays due to changing wind patterns and weather systems.

What is the typical rainfall amount considered ‘light,’ ‘moderate,’ or ‘heavy’ in Delhi?

In Delhi, 'very light' rainfall is up to 2.4mm in 24 hours, 'light' is 2.5–15.5mm, 'moderate' is 15.6–64.4mm, and rainfall above that is considered 'heavy.' These classifications help authorities assess risk and issue appropriate warnings.