West Bengal braces for a sharp weather divide this week, as thunderstorms and gusty winds loom over the northern parts under the influence of an upper-air cyclonic circulation over east Bihar, while the southern districts face rising heat and humidity triggered by a dry westerly flow.

Forecast for June 3

In south Bengal, light to moderate rain or thundershowers are very likely at a few places in Murshidabad, Nadia, Birbhum and the North and South 24-Parganas, with one or two spells elsewhere.

Thunderstorms accompanied by lightning and wind speeds of 30–40 kmph may strike isolated pockets of Birbhum, Murshidabad, Nadia and both 24-Parganas districts.

A localised heat wave is expected over South 24-Parganas and West Medinipur, while hot and humid weather will prevail over Kolkata, Howrah, North 24-Parganas, East Midnapore and Jhargram.

North Bengal faces light to moderate rain or thundershowers at most places in Kalimpong, Darjeeling, Jalpaiguri, Cooch Behar and Alipurduar, and at many places elsewhere in the region.

Thunderstorms with lightning and gusts of 40–50 kmph are possible in one or two areas across all districts.

Forecast for June 4

Light to moderate rain or thundershowers forecast for Murshidabad, Nadia, Purulia, Bankura, East and West Bardhaman and both 24-Parganas and isolated falls elsewhere.

Birbhum, Murshidabad and Nadia may witness thunder squalls reaching 40–50 kmph, while 30–40 kmph gusts could sweep the remaining districts.

The heat-wave belt over South 24-Parganas and West Medinipur will persist and sultry conditions are set to grip Jhargram, Kolkata, Howrah, East Medinipur and North 24-Parganas.

Across north Bengal, light to moderate rain or thundershowers are likely at most places.

Thunderstorms, lightning and winds of 50–60 kmph may lash Malda, North Dinajpur and Jalpaiguri, where North Dinajpur also faces the threat of heavy rainfall exceeding 7 cm.

Gusts of 30–40 kmph are expected elsewhere, with heavy rain of more than 7 cm possible over Darjeeling.

Forecast for June 5

The wet spell will embrace all districts of south Bengal with light to moderate rain or thundershowers.

Thunderstorms bearing lightning and winds of 40–50 kmph could hit Jhargram, Kolkata, Howrah, Hooghly, East and West Medinipur and both 24-Parganas, while 30–40 kmph squalls are forecast for the remaining districts.

In north Bengal, light to moderate rain or thundershowers are very likely at many places across Kalimpong, Darjeeling, Jalpaiguri, Cooch Behar and Alipurduar and at a few places elsewhere.

North Dinajpur and Jalpaiguri may experience thunderstorms with lightning and 40–50 kmph gusts and the rest of the region can expect winds of 30–40 kmph.

The heat is expected to remain tolerable for the general public but poses a moderate health risk to infants, the elderly, those with chronic ailments and people who work long hours in the sun.

Residents are urged to avoid prolonged exposure, particularly between 11 am and 4 pm.; to wear light-coloured, loose cotton clothing and protect the head with a cloth, hat or umbrella; to drink ample water even when not thirsty; and to recognise signs of heat stress such as weakness, dizziness, headache, nausea, sweating or cramps and seek immediate medical attention if these occur.

Thunderstorms with lightning and gusty winds may damage standing crops, vegetables and horticultural produce and pose a risk of lightning strikes in open fields, while urban traffic disruptions are possible.

The public should move indoors when thunder roars, avoid sheltering under trees or electric poles, stay away from water bodies and cooperate with any traffic regulation that may be imposed.