There are prospects that the South-west monsoon in this year may commence on 25th May. The ex-director of the Indian Weather Bureau and researcher Joseph explained regarding this:
Normally, the South-west monsoon is slated to start from 1st June and continue until 30th September.
However, this current year, the estimates show that there are good prospects that the South-west monsoon may start in Kerala on 25th May.
The hot air phenomenon blowing over the surface of the Pacific Ocean is called El Nino. This phenomenon affects the Indian monsoon seasons. It is expected that the during the 2nd phase of the coming South-west monsoon, El Nino phenomenon may affect the monsoon. This may lead to a shortage in rainfall from the South-west monsoon as compared to the average rainfall expected.
Generally, well before the South-west monsoon is set to start on 1st June, rain clouds will start gathering over the Bay of Bengal from 21st April. The satellite pictures reveal that this is likely to occur now. So, it is expected that the South-west monsoon may start earlier 25th May.