IMD forecasts below-normal rainfall in August-September

India as a whole is most likely to witness below-normal rainfall during the second half of the southwest monsoon from August to September, the India Meteorological Department (IMD) said in its monthly forecast issued on Friday.

The rainfall is expected to be less than 94 per cent of the Long Period Average (LPA), it said.

LPA refers to the rainfall recorded over a particular region in a given period, such as a month or a season, averaged over a long period, typically 30 to 50 years.

The LPA of rainfall over the country as a whole during the August to September period, based on historical data from 1971 to 2020, is 422.8 mm.

In a statement, Dr Mrutyunjay Mohapatra, director general of meteorology at the IMD, said, “During this (August-September) period, below-normal rainfall is very likely over many parts of the country, except some parts of peninsular India, central India, northern parts of northwest India, and east and northeast India, where normal to above-normal rainfall is likely.”

For the month of August, rainfall over the country as a whole is also expected to be below-normal, with less than 94 per cent of the LPA, the IMD said.

The LPA of rainfall over India during August, based on the 1971-2020 data, is 254.9 mm.

Currently, India is facing a rainfall deficit of 13 per cent for the period between June and July. At the end of June, this figure had stood at 35.4 per cent.

“The reduction in rainfall deficit happened due to good rainfall activity in July,” Dr Mohapatra said.

While the average rainfall in July is 280.5 mm, the country received 283.3 mm rainfall during the month this year.

There were two main reasons for this. First, four low-pressure systems (LPS) formed over the Bay of Bengal during the month, and two of them intensified into depressions.

There was also a rise in the number of LPS days. While typically July sees 13.5 LPS days, this time there were 24 LPS days.

Second, the Madden-Julian Oscillation (MJO) was in a favourable phase initially in the month. The MJO is a moving system of wind, cloud and pressure that brings rain as it circles the equator.

In a favourable phase, it brings more clouds to the south of India, which are then carried northwards by the monsoon winds, leading to enhanced rainfall.

During the later part of July, however, the MJO was in an unfavourable phase.

According to the IMD, July also saw the highest number of extremely heavy rainfall events (more than 204.5 mm of rainfall) in the past five years. In 2026, there were 269 of such events; in 2025, 84; in 2024, 194; in 2023, 205; and in 2022, 129.

Dr Mohapatra pointed out that the extremely heavy rainfall events in July were largely concentrated in Odisha, Gujarat and Maharashtra.

While India as a whole saw slightly above-normal July rainfall this year, cumulative rainfall over the Southern Peninsula was the 10th lowest (152.6 mm) since 1901.

As a result, according to Dr Mohapatra, the region saw the highest minimum temperature (24.68 degrees Celsius) for July this year since 1901. The normal minimum temperature in the Southern Peninsula for this month is 23.68 degrees Celsius.