Monsoon season ends with 109% excess rainfall; August sets record with 127% excess rain: IMD

India received the third-highest monsoon rainfall of the past three decades in 2020 with the monsoon season ending with 109% more than the average rainfall, India Meteorological Department said on Thursday.

The all India southwest monsoon rainfall this year was the third-highest since 1990 after 112% of the average rainfall in 1994 and 110% in 2019.

Since 2019 was also an excess rainfall year, this is also for the first time in six decades that two consecutive years ended with excess rainfall after 1958-1959.

August was particularly bountiful as there were five back-to-back low-pressure systems in the Bay of Bengal resulting in 127% more than average rainfall—a record in the past four decades. Twenty-eight out of 31 days in August were low-pressure days.

Such a huge quantity of August rainfall was seen last time 44 years ago in 1976 when there was 128.4% more than average rainfall. It is also the fourth highest August rainfall in the past 120 years, causing 2-3 spells of riverine floods in Odisha, Telangana, Madhya Pradesh, south Gujarat and south Rajasthan.

“The 2020 monsoon performance was good as expected with the help from La Niña (opposite to El Nino conditions) that involves cooling of the Pacific sea surface. It will help Kharif (summer) crops and Indian economy to some extent,” M Rajeevan, Secretary, Ministry of Earth Sciences, told DH.

For four consecutive weeks in August, the country received excess rain, which wipes out not only the deficiencies seen in July but led to more-than-predicted rainfall in three out of four regions.

Northwest India is the only region that ended with a deficient rainfall of 84% of the average as against the predicted value of 107%.

The other three regions were showered with copious rainfall with central India receiving 115% of average rainfall (103% was IMD forecast), northeast India getting 107% (forecast: 96%) and peninsular India receiving 129% of its average rainfall as against 102% predicted by the IMD.

Out of 36 meteorological subdivisions, only five recorded deficient rainfall with west Uttar Pradesh registering the worst shortage of 37%.

The withdrawal of monsoon from the western parts of northwest India began on Sept 28, after a delay of 11 days, due to an active monsoon system following the formation of two low-pressure systems in September.

As on October 1, southwest monsoon has withdrawn from Punjab, western Himalayas, Haryana, Chandigarh, Delhi and parts of Rajasthan and Uttar Pradesh. "The process of withdrawal should be completed by October 15,” Rajeevan said.