Wettest May for India in 125 years so far as rain, storms wreak havoc

This May is, thus far, the wettest in India in 125 years, the period for which India Meteorological Department (IMD) has published gridded data, which allows detailed analysis of rainfall.

- Abhishek Jha

An HT analysis of this data shows that the month will end up as the third wettest May since 1901 even if there is no rain in the remaining four days. While the early arrival of the monsoon has aided this trend, frequent storms across the country even before monsoon's arrival are a big reason.

According to IMD's gridded data-it gives average rain for grids or boxes bound by two latitudes and longitudes 0.25 degrees apart that can be aggregated to calculate average rain for India - India has received an average of 100.7 mm rain up to 8.30am on May 27.

This is the highest rainfall for the first 27 days of May (rain for a particular date in IMD's data is rain in the 24 hours up to 8.30am on the date).

To be sure, IMD's official report for the month may find a somewhat different rank because it does not aggregate the number for India from gridded data but directly from the data from weather stations.

However, that is unlikely to change the broad trend.

For example, the rain this May is 88.5% more than the 1971-2020 average of rain for the May 1-27 period. IMD considers the average for the 1971-2020 period as the Long Period Average (LPA) currently for tracking rain's performance. The LPA for the first 27 days of May is 53.4mm and that for the month in its entirety is 63.3mm. This means that India has already received more rain this month than it usually does by May 31.