Thiruvananthapuram: Kerala is likely to witness widespread rainfall in the upcoming days ahead of the southwest monsoon's onset, the India Meteorological Department (IMD) said on Thursday.

A yellow alert was declared in Idukki and Pathanamthitta districts on Thursday and Friday. A yellow alert means heavy rainfall between 6 and 11 cm.

Thunderstorm with lightning and gusty winds speed reaching 30- 40 Kmph is very likely to occur at one or two places in Kerala and Lakshadweep till June 3.

According to the Met department, the Southwest Monsoon will reach Kerala by June 4.

Pre-monsoon rains are likely to continue in the state till the arrival of the monsoon with southern districts receiving more rainfall.