Expect a very wet September, says IMD, cautions hill states

NEw new delhi: thither is potential to be above-normal rain down o'er the country as a whole during September at 109% of the long period average (LPA), India Meteorological Department forecast on Sunday.Geographically, most parts of the country are likely to receive normal to above-normal rainfall. However, some parts of Northeast and East India, many areas of extreme South Peninsular India and some parts of northernmost India, are likely to receive below-normal rainfall, IMD has said.The LPA of rainfall over the country as a whole during September based on data from 1971-2020 is about 167.9 mm. “We are anticipating good, above normal rainfall during the month. This can lead to episodic occurrence of cloudbursts, mudslides, landslides etc. Authorities should be prepared,” M Mohapatra, director general warned. IMD had issued the long range forecast for the 2025 southwest monsoon seasonal rainfall over the country in May when it said rainfall is likely to be 106% of the LPA with a model error of ±4%.“Above-normal rainfall can significantly benefit agriculture and water resources but also brings potential risks such as flooding, landslides, surface transport disruptions, public health challenges, and ecosystem damage. To manage these risks effectively, it is essential to reinforce infrastructure, utilise IMD’s early warnings, enhance surveillance and conservation efforts, and establish robust response systems in vulnerable sectors,” IMD said.During September 2025, average day temperatures are likely to remain normal to below normal in many regions of west-central, northwest and south India. It is likely to be above normal over many parts of east-central, east and northeast India and some parts of northwest India and western coastal region.In September 2025, the monthly average night temperatures are expected to be normal to above normal over most parts of the country. However, below-normal minimum temperatures are likely over some parts of northwest India and southern peninsular India.Currently, neutral El Niño–Southern Oscillation (ENSO) conditions are prevailing over the equatorial Pacific region. Forecasts from the Monsoon Mission Climate Forecast System (MMCFS), along with other climate models, suggest that these neutral conditions are likely to persist till the end of the monsoon season. But, there are also indications that temporary La Nina conditions are likely to develop in October-November-December period.At present, neutral Indian Ocean Dipole (IOD) conditions are prevailing over the Indian Ocean. Climate models indicate that weak negative IOD conditions are likely to develop towards the end of the monsoon season.El Niño events typically suppress rainfall by weakening monsoon winds and reducing moisture transport from the oceans. Conversely, La Niña conditions generally enhance monsoon activity by strengthening the pressure gradient that drives monsoon circulation. Neutral ENSO conditions, as currently prevailing, provide a favourable environment for normal monsoon performance, allowing regional weather systems to operate without large-scale interference from Pacific Ocean temperature anomalies.August mayhemRainfall over northwest India for August was 265 mm, highest since 2001 and 13th highest since 1901. Rain over the South Peninsula was also the third highest since 2001 and eighth highest since 1901, according to IMD.Since June 1, there is 6.1% excess rainfall over the country with 26.7% excess over northwest India; 17.8% deficiency over east and northeast India; 8.6% excess over central India and 9.3% excess over south peninsular India.There were five active disturbances which impacted northwest India in August and interacted with monsoonal weather systems leading to “active to vigorous” rainfall over the second half of August especially in the Himalayan states.Mohapatra also said 1980 onwards there is an increasing trend in rainfall in September. In the last 4-5 years this is increasing further. “September is a transitional month. One factor may be the interaction of western disturbances with monsoon during this month,” he said.Mohapatra warned there is likely to be extensive, heavy rainfall during the next two weeks over north India, central India and Indo-Gangetic plains region.