Monsoon rainfall from June 1 till August 31 has shown a deficiency of 9 per cent compared to the long period average (LPA) while the monthly rainfall over the country as a whole during September 2021 is most likely to be above normal, said the Indian Meteorological Department (IMD) on Wednesday.

Announcing the forecast for September over the country, IMD Director General Mrutyunjay Mohapatra said the rainfall average over the country as a whole during September 2021 is most likely to be above normal, that is more than 110 per cent of the LPA.

The LPA of rainfall for September is nearly 170 mm and is based on the data between 1961 and 2010.

Northwest India and central India witnessed a deficit of -14 per cent, east and northeast India witnessed a deficit of -8 per cent while southern peninsular India witnessed 8 per cent more rainfall compared to normal.

Much of the total season’s deficit was due to the deficient rainfall in August, the IMD data showed.

“Considering the expected above normal rainfall activity during September 2021, the current deficiency of 9 per cent in seasonal rainfall during June to August is very likely to reduce and accumulated seasonal rainfall during June 1 to September 30 is expected to be around the lower end of normal,” Mohaptra said.

The spatial distribution of probabilistic forecasts for tercile categories (above normal, normal, and below normal) for the September rainfall forecast suggests that above normal to normal rainfall is likely over many areas of central India; normal to below normal rainfall is most likely over many areas of northwest and northeast India and southernmost parts of peninsular India, he added.

Since 1901 during the monsoon season, there were 23 years when there were negative IOD conditions (Indian Ocean Dipole, a condition arising out of the difference between sea surface temperatures at different places in the Indian Ocean). Of the 23 negative IOD years, in six years (26 per cent) each, southwest monsoon saw deficient rainfall and excess rainfall category, the IMD Director General said.