The onset of the southwest monsoon over Kerala happened on June 8, 2023, a week later than its normal onset date of June 1. Monsoon 2023 has almost covered the entire country by June 30 — about a fortnight earlier than usual of July 15.
Last year, the monsoon had arrived early — the India Meteorological Department (IMD) had declared the onset on May 29, 2022. However, the monsoon had arrived on June 8 in 2019 and 2016 as well.
The onset of the monsoon over the state signals the beginning of the four-month (June-September) southwest monsoon season in India. It advances northwards, usually in surges and covers the entire country around July 15.
Source: IMD
This year, the monsoon had a decent progress over southern, north eastern and some parts of eastern India for a few days. However, the Bay of Bengal branch of the monsoon winds stalled between June 12 and June 21 while the Arabian Sea branch stalled between June 11 and June 23.
Two kinds of extreme weather events were reported across the country while the winds were stalled — both floods and heat waves.
While heatwaves raged in eastern and some southern states from June 11, the passing of cyclone Biparjoy from June 15 caused heavy rainfall in western India and northwestern India.
This brought respite from heat, but caused flood like situations and landslides, especially in the Himalayan states. The eastern parts of the country continued being under heat stress till the monsoon finally progressed around June 21-22.
Active monsoon conditions in North East India caused floods and flood-like situations, though many states still faced a deficit by the end of the month. After the monsoon started progressing further between June 21 and June 23, it made rapid strides and covered the rest of the country within the week.
The rapid progress meant that Delhi and Mumbai received their first monsoon rains at the same time, an event that has occurred after 60 years. Experts say this was a new way of progress of the monsoon.
As of June 30, the monsoon winds have covered all of India, apart from a few areas in northern Rajasthan and eastern Haryana.
“Conditions are favourable for further advance of southwest monsoon into remaining parts of the country (that is, remaining parts of Rajasthan and Haryana and Punjab) during next two days,” the IMD stated in a press note released in the afternoon of June 30.
Even as the monsoon has almost covered the entire country in 22 days rather than the normal duration of 38 days, 53 per cent of the districts are suffering from deficient or large deficient rainfall.
The all-India rainfall deficit is 13 per cent with 14 states and Union territories having received ‘deficient’ rainfall and two states having received ‘large deficient’ rainfall.
Rainfall is classified as deficit by the IMD when it is 19 per cent or less (-19 per cent) than the average amount. It is ‘large deficit’ or ‘large deficient’ when it is more than -59 per cent.
Rainfall between -19 per cent and 19 per cent is classified as ‘normal’ and between 20 per cent and 59 per cent is ‘excess’. When rainfall is 60 per cent more than normal, it is categorised as ‘large excess’.
Some states such as Bihar (-69 per cent) and Kerala (-60 per cent) recorded large deficits in rainfall between June 1 and June 29.