The southwest monsoon arrived over most parts of Andaman and Nicobar Islands on Monday, the India Meteorological Department said. This signals the beginning of four-month seasonal rains in India.

In a press release, the weather department said that conditions were favourable for the southwest monsoon to advance further into parts of southern and east central Bay of Bengal regions and the entire Andaman and Andaman Islands in the next three days.

The agency predicted isolated heavy rainfall accompanied by thunderstorm and lightning over Andaman and Nicobar Islands during the next five days.

The onset of monsoon happened a day later than the weather agency’s earlier prediction that the seasonal rains would cover Andaman and Nicobar by Sunday, reported PTI. It has also forecast onset of southwest monsoon in Kerala on May 27, five days ahead of its normal arrival time.

In its report, the weather agency said that southwesterly winds are likely to lead to heavy to very heavy rainfall in Arunachal Pradesh, Assam, Meghalaya, West Bengal and Sikkim during the next four to five days.

It also predicted isolated extremely heavy rainfall in Meghalaya on Monday and Tuesday and isolated heavy rains in Mizoram and Tripura between May 16 and May 18.

A cyclonic circulation present over Lakshadweep and north Tamil Nadu coast will bring fairly widespread isolated heavy to very heavy rainfall with thunderstorm and lightning in Kerala and Karnataka during the next five days, the weather department added.