India Aug-Sep Rainfall Likely Below Normal as El Niño Strengthens

Rainfall across India is likely to be below normal during August-September, the second half of the southwest monsoon season, as El Niño conditions strengthen, the India Meteorological Department said on Friday.

Rainfall of less than 94% of the long-period average is categorised as below normal. The long-period average for August-September, based on data from 1971 to 2020, is 422.8 mm.

Below-normal rainfall is likely across many parts of the country. However, some areas of peninsular and central India, northern parts of northwest India, and east and northeast India may receive normal to above-normal rainfall, IMD said.

Rainfall in August alone is also expected to be below normal. The long-period average for the month is 254.9 mm.

Most parts of the country are likely to receive below-normal rainfall in August, barring many areas of eastern peninsular India, some parts of northwest and central India, and isolated pockets of east and northeast India where normal to above-normal rainfall is expected. 

The forecast could add to concerns over kharif sowing and reservoir replenishment after cumulative monsoon rainfall remained deficient through much of June and July.

Moderate El Niño conditions currently prevail over the equatorial Pacific Ocean, with sea-surface temperatures above normal across its central and eastern parts. These conditions are expected to strengthen during the remainder of the southwest monsoon season, according to forecasts from the Monsoon Mission Coupled Forecast System, IMD said. 

Neutral Indian Ocean Dipole conditions currently prevail and are likely to persist through the remaining monsoon season. Some international forecasting agencies, however, expect a positive Indian Ocean Dipole to develop in September.

A positive Indian Ocean Dipole can sometimes support rainfall over India, but the IMD did not indicate whether it would be sufficient to offset the impact of strengthening El Niño conditions.

The IMD will release its rainfall forecast for September by the end of August.