Bay of Bengal depression to bring heavy rain to South Bengal by August 15
Synopsis
A Bay of Bengal low-pressure system is deepening into a depression just days before Independence Day, placing South Bengal's coastal districts on high alert. With winds up to 70 kmph and a fishing ban through 15 August, the next 48 hours are critical for communities along West Bengal's coastline.
Key Takeaways
A Bay of Bengal low-pressure area is likely to intensify into a deep depression , the IMD warned on 13 August .
Yellow alerts have been issued for South 24 Parganas and Purba Medinipur ; coastal and western districts remain on alert through Friday.
Wind speeds of 50–70 kmph are forecast; fishermen have been advised not to venture to sea until 15 August .
Kolkata is under a yellow alert with thunderstorms and moderate rainfall expected.
North Bengal districts including Malda , Dakshin Dinajpur , and Uttar Dinajpur are under yellow alert for light to moderate rain with thunderstorms.
Rainfall is expected to ease across South Bengal by Saturday and Sunday , with only isolated showers forecast.
A low-pressure area over the Bay of Bengal is expected to deepen into a deep depression, triggering heavy rainfall across multiple districts of South Bengal over the next several days, the India Meteorological Department (IMD) warned on Thursday, 13 August. The system has already prompted a fishing ban and rough sea advisory along the West Bengal coast through 15 August.
Weather System and Current Conditions
According to the IMD, a combination of cyclonic circulation and the low-pressure system has generated adverse weather over the northern Bay of Bengal and adjoining coastal stretches of West Bengal. Wind speeds are forecast to range between 50 kmph and 70 kmph from Thursday onwards, prompting authorities to urge coastal communities to remain on high alert and monitor official advisories closely.
The Regional Meteorological Centre (RMC) in Kolkata has forecast widespread rainfall across South Bengal for at least the next three days. North Bengal is expected to receive comparatively lighter rainfall initially, though weather activity there is likely to intensify over the weekend.
What Officials Said
Habibur Rahman Biswas, Director of the Eastern Region at the RMC, said the low-pressure area is expected to deepen into a depression, raising the likelihood of heavy rainfall across South Bengal through Saturday. 'Sea conditions are expected to remain rough during this period,' he added.
District-Level Alerts
The IMD has issued a yellow alert for heavy rainfall in South 24 Parganas and Purba Medinipur districts on Thursday, with thunderstorms and gusty winds of 30–40 kmph likely across most of South Bengal. The yellow warning for coastal and western districts will remain in force through Friday. Rainfall activity is expected to ease on Saturday and Sunday, with only isolated light showers forecast and no major weather warning anticipated.
In North Bengal, no heavy rainfall warning has been issued for Thursday. However, Malda, Dakshin Dinajpur, and Uttar Dinajpur are under a yellow alert for light to moderate rain with thunderstorms. Isolated heavy showers are also possible in parts of Jalpaiguri and Alipurduar districts, while other areas may see light to moderate rainfall, lightning, and gusty winds up to 30–40 kmph.
Kolkata on Alert
Kolkata is under a yellow alert, with thunderstorms and moderate rainfall expected through the day. On Wednesday, the city recorded a maximum temperature of 31.09 degrees Celsius — marginally below normal — while the minimum settled at 27.09 degrees Celsius, approximately one degree above the seasonal average.
Fishing Ban and Coastal Advisory
The Met Office has advised fishermen not to venture into the sea until 15 August, given the rough sea conditions expected to persist as the system intensifies. Authorities have urged coastal communities to stay ashore and follow official weather updates closely. This kind of pre-monsoon and mid-monsoon low-pressure intensification over the Bay is a recurring pattern for West Bengal, with similar systems in recent years causing significant flooding in low-lying coastal districts.
Weather officials will continue to monitor the system's track and intensity through the weekend, with updated advisories expected as the depression develops further.
Point of View
Yet district-level disaster preparedness in coastal West Bengal — particularly in South 24 Parganas — remains inconsistently implemented. A yellow alert is a moderate warning, but the combination of 70 kmph winds and a deepening depression close to a national holiday weekend, when administrative response can be slower, raises the stakes. The fishing ban through 15 August is the right call, but enforcement along West Bengal's sprawling coastline has historically been patchy. If the system deepens faster than projected, the window for evacuation of vulnerable coastal communities narrows sharply.
NationPress
13 Aug 2026
Frequently Asked Questions
What is the Bay of Bengal low-pressure system and how serious is it?
A low-pressure area over the Bay of Bengal is expected to intensify into a deep depression, according to the IMD. This brings the risk of heavy rainfall, winds of 50–70 kmph, and rough sea conditions along West Bengal's coast through at least 15 August.
Which districts in South Bengal are under a weather alert?
The IMD has issued yellow alerts for South 24 Parganas and Purba Medinipur on Thursday, with the warning extending to coastal and western districts through Friday. Thunderstorms with gusty winds of 30–40 kmph are likely across most of South Bengal.
Is Kolkata affected by the weather warning?
Yes, Kolkata is under a yellow alert for thunderstorms and moderate rainfall. On Wednesday, the city recorded a maximum temperature of 31.09 degrees Celsius and a minimum of 27.09 degrees Celsius, both close to seasonal norms.
Why have fishermen been asked to stay off the sea?
The Met Office has advised fishermen not to venture into the sea until 15 August due to rough sea conditions and wind speeds expected between 50 and 70 kmph as the low-pressure system deepens into a depression.
When will the rain ease in South Bengal?
According to the RMC, heavy rainfall activity is expected to ease by Saturday and Sunday, with only isolated light showers forecast and no major weather warning anticipated for those days.
