Southwest monsoon is a 4 month long season (June-September). Over the Indian Sub-Continent, the monsoon activity is observed for sometime, in May and October as well. However, seasonal long period average (LPA) rainfall is accounted for, between 01stJune and 30th September. Month of June is the least rainiest with an LPA of 165mm (appx), followed by September with 170mm of rainfall. July and August are the core monsoon months with LPA of 280mm and 255mm(appx) respectively. Simultaneous failure of these core months invariably leads to drought. However, decent rainfall in both these months ensures ‘normal’ or ‘above normal’ monsoon for the country.
Both the core monsoon months delivering adequate rainfall is not a common feature. In the last 25 years, only on 4 occasions, the rainfall was in excess of 100% of LPA, during the core monsoon months. Another inference during such episodes being, a ‘normal’ or ‘above normal’ monsoon season for the country with total rainfall of >/= 100% of LPA.
In the last 40 years, 1988 and 1994 had been the best performer during the core monsoon months. July and August delivered exceptionally well during these years with monthly rainfall in excess of 110%. Monsoon season also ended up in excess with seasonal rainfall of 113% and 112% of LPA, respectively. Year 2022 has done rather well during the core months, so far. Though, the rainfall may reduce now, in the remaining days of August, but the month will end up with surplus rainfall.
