For a third year in a row, India is expected to receive more than its usual quota of rain in September, a month that usually marks the retreat of the monsoon’s four-month sojourn over the country.
“The rainfall averaged over the country as a whole during the month of September 2022 is most likely to be above normal or greater than 9% of the Long Period Average (LPA),” the IMD said in its updated forecast. The LPA of rainfall over the country during September based on data of 1971-2020 is about 167.9 mm.
Beginning 2019, monsoon in India has returned surpluses, barring a slight dip last year. The June-September rainfall that year was 10% more than the 88 cm that India usually gets. Though June saw deficit rain, the months of July and August returned extra rain, with September registering 52% more rain than normal.
In 2020, India saw 9% more rain with August registering 27% more rain and September 4% more than its usual quota.
The rainfall over country as a whole, in 2021, was 1% less than normal though rainfall in September was a remarkable 35% above what is usual.
This year the monsoon is already in surplus by about 6% and a vigorous September, is likely to see India post yet another year of surplus rain. Three years of above normal rain in a block of four years is unprecedented in more than a century of IMD’s record keeping, data suggests.
La Nina effect
Why September has taken a shift towards excess rain is as yet unknown, say meteorologists, though the active spells in the recent years is due to an active La Nina, which began around September 2020. La Nina, marked by cooler temperatures in the Central Pacific, usually means heavier monsoonal rains.
“Currently, La Niña conditions are prevailing over the equatorial Pacific region. The latest forecast indicates that the La Niña conditions are likely to continue up to the end of the year. Other climate models are also indicating continuation of La Niña conditions during the upcoming season,” the IMD added.
