Heavy Rain Likely Across West Bengal From September 22 as Bay Low-Pressure System Intensifies

KalimNews, Kolkata, September 21: West Bengal is bracing for an extended spell of rain and thunderstorms from Tuesday, September 22, as a low-pressure system over the Bay of Bengal is expected to strengthen and move towards the Odisha-Andhra Pradesh coast, according to the India Meteorological Department (IMD). 

The system, currently located over the east-central Bay of Bengal and adjoining north Andaman Sea, is forecast to intensify into a depression on September 21 and a deep depression over the west-central Bay of Bengal on September 22 before moving towards the north Andhra Pradesh-south Odisha coast around September 23.

The developing system is expected to bring widespread rainfall, thunderstorms, lightning and gusty winds to several parts of West Bengal during the coming week. 

South Bengal to see widespread rain from September 22

According to the latest West Bengal forecast, light to moderate rain or thundershowers are likely at many places across South Bengal on September 21-22, with thunderstorms, lightning and gusty winds of around 30-40 kmph possible in one or two places.

The weather is expected to become more active from September 22.

On September 22-23, heavy rainfall of 7-11 cm is likely at isolated places in South 24 Parganas, East Midnapore, West Midnapore and Jhargram. Gusty winds of 40-50 kmph are possible in South 24 Parganas and East Midnapore, while other districts may experience thunderstorms and winds of 30-40 kmph.

The rain belt is expected to remain active on September 23-24. Heavy rainfall of 7-11 cm is forecast in parts of South 24 Parganas, East Midnapore, West Midnapore, Jhargram, Murshidabad, Birbhum, West Burdwan and Purulia.

On September 24-25, heavy rain is expected at isolated places in South 24 Parganas, East Midnapore, West Midnapore, Jhargram, Bankura and Purulia.

The IMD has also warned of thunderstorms, lightning and gusty winds across South Bengal during this period. 

Rain likely to continue after September 25

The weather system is not expected to disappear immediately after the main September 22-25 spell.

On September 25-26, widespread light to moderate rain and thundershowers are likely across South Bengal, with isolated heavy rain possible in South 24 Parganas, East Midnapore, West Midnapore, Jhargram, Bankura, Birbhum, West Burdwan and Purulia.

On September 26-27, rain is expected to continue at many places, although the intensity may gradually become less widespread compared with the peak period.

The IMD's current seven-day warning therefore indicates that South Bengal could experience an extended wet spell from September 22 through September 27. 

North Bengal faces heavier rain risk

North Bengal is also expected to experience increasing rainfall from September 22.

On September 22, light to moderate rain or thundershowers are likely at many places, with thunderstorms and gusty winds possible over parts of Malda and the two Dinajpur districts.

The situation is expected to become more active on September 23-25, when most parts of North Bengal could receive light to moderate rain.

Heavy rain is forecast in Jalpaiguri and Darjeeling during September 23-25.

The most significant warning currently covers September 25-26, when Jalpaiguri could receive heavy to very heavy rainfall of 7-20 cm at isolated locations. Heavy rain is also possible in Darjeeling, Kalimpong, Alipurduar, Cooch Behar and North Dinajpur.

Rain is expected to continue on September 26-27, with heavy rainfall possible over Jalpaiguri, Darjeeling and Kalimpong.

The IMD has warned of possible landslides in the hilly areas of Darjeeling and Kalimpong during periods of intense rainfall. 

Kolkata and adjoining areas

Kolkata and neighbouring districts are likely to remain under the influence of the weather system from September 22.

The main risks for the city and surrounding urban areas are expected to be periods of heavy rain, lightning, gusty winds and temporary waterlogging, particularly in low-lying areas and underpasses.

The IMD has also advised caution during thunderstorms and lightning, particularly in open areas. 

Bay of Bengal remains rough

The developing depression is also expected to produce strong winds over the Bay of Bengal.

Squally winds are forecast to increase to around 55-65 kmph, gusting to 75 kmph, over the west-central and adjoining northwest Bay on September 23 and continue into September 24.

Along and off the West Bengal coast, winds of around 40-50 kmph, gusting to 60 kmph, are likely from September 23-25.

Sea conditions are expected to remain rough to very rough over the Bay and along the West Bengal coast during the period. Fishermen have been advised not to venture into the deep sea from September 21, with those already at sea advised to return to the coast by September 21 night. 

What happens after September 27?

The present IMD seven-day forecast provides the highest-confidence guidance through September 27. Beyond that date, a precise district-level forecast cannot yet be stated with the same confidence.

However, given the continuing monsoon conditions and the possibility of further weather systems developing over the Bay of Bengal, rain and thundershower activity may continue into the last week of September and early October.

Any fresh low-pressure area or circulation forming over the Bay could modify the rainfall pattern substantially. Therefore, forecasts for September 28-October 5 should be treated as an outlook rather than a fixed day-by-day prediction and updated with subsequent IMD bulletins.

Two-week outlook at a glance

Period	Expected weather in West Bengal
Sept 21	Rain/thundershower activity; thunderstorms possible
Sept 22	Rain increases; heavy rain begins in parts of South Bengal
Sept 23	Widespread rain; heavy rain in several South Bengal districts; North Bengal becomes wetter
Sept 24	Widespread rain; heavy rain in several districts
Sept 25	Heavy rain continues; very heavy rain risk increases in parts of North Bengal
Sept 26	Widespread rain; heavy to very heavy rain possible in North Bengal
Sept 27	Rain continues; heavy rain possible in parts of North Bengal
Sept 28-30	Rain/thundershower activity may continue, but confidence in exact distribution is lower
Oct 1-5	Monsoon showers remain possible; specific heavy-rain areas will depend on subsequent weather systems

The current IMD warning supports the September 21-27 portion of this outlook; the September 28-October 5 portion should be regarded as a lower-confidence extended outlook rather than a confirmed forecast. 

Public safety advice

Residents should exercise caution during thunderstorms and lightning, avoid taking shelter under trees or near electric poles, and avoid contact with water bodies during lightning activity.

People living in low-lying urban areas should also remain alert for temporary waterlogging between September 22 and 25. In the hills of Darjeeling and Kalimpong, travellers should be alert to possible landslides during periods of intense rain.

The latest district-wise warnings should be checked before undertaking travel, particularly during the September 23-26 period. The IMD maintains a live district-warning system for this purpose.