If you were hoping the weekend would give Kolkata a dry break, the India Meteorological Department has other plans. The Regional Meteorological Centre at Alipore issued its seven-day outlook on Saturday morning, September 19, and it keeps the city under a thunderstorm warning through Sunday, with rain or thundershowers very likely at many places across South Bengal on both days. Further out, a new low-pressure area is expected to take shape over the north Andaman Sea by Saturday evening, and while its track points towards Odisha and Andhra Pradesh rather than Bengal, IMD’s national bulletin already pencils in a wetter spell for Gangetic West Bengal around September 23 and 24. In short: umbrella today, umbrella tomorrow, and keep an eye on the middle of next week.
What IMD Is Forecasting for Kolkata This Weekend
The Alipore office’s district-wise forecast for Kolkata is the same for Saturday and Sunday: light to moderate rain or thundershowers very likely at many places, with a warning for thunderstorm, lightning and gusty winds of 30 to 40 kmph at one or two places. The warning covers Saturday from 8:30 am through 8:30 am Sunday, and then Sunday through 8:30 am Monday. The same thunderstorm flag applies to every district in South Bengal, from Howrah and Hooghly to the two 24 Parganas, both Midnapores, Bankura, Purulia, Birbhum, Murshidabad and Nadia.
The city has already had a taste of what to expect. IMD’s national summary lists Kolkata-Alipore among the significant rainfall stations on Friday, with 3 cm recorded between 8:30 am and 5:30 pm on September 18, and the department had flagged moderate to severe lightning activity over Gangetic West Bengal the same day. Media forecasts for Saturday put the maximum near 33 degrees Celsius with humidity in the 90s, which means the air will feel far hotter than the thermometer suggests in the gaps between showers.
Monday and Tuesday Look Quieter
There is some relief in the outlook. For Monday, September 21, and Tuesday, September 22, IMD downgrades Kolkata to light to moderate rain or thundershowers “likely at a few places”, and the thunderstorm warning drops away entirely for the city and every other South Bengal district. That matters locally because Monday is the Karam Puja holiday, giving many people a long weekend, and the early part of the week looks like the better window for a day out, a shopping trip or pandal-side errands before the next round of rain arrives.
The New Low Pressure Over the Andaman Sea
The bigger story sits well to the south-east of Kolkata. According to IMD’s all-India bulletin issued on Friday night, an upper-air cyclonic circulation that had been sitting over north Thailand moved westwards and emerged over the north Andaman Sea at 5:30 pm on September 18. It extends up to 7.6 km above sea level, a sign of a system with real depth. Under its influence, IMD expects a low-pressure area to form over the same region around the evening of September 19. From there, the system is likely to intensify gradually and move west-northwestwards towards the south Odisha and north Andhra Pradesh coasts over the following three to four days.
That track keeps the core of the system away from the Bengal coast, which is why RMC Kolkata has issued no fishermen warning and no port warning for West Bengal at this stage. Odisha is the state in the firing line, with heavy to very heavy rain flagged there for September 23 and 24. But Kolkata sits on the wet northern flank of any system that moves into the west-central Bay, and IMD’s seven-day rainfall table upgrades Gangetic West Bengal to fairly widespread rain on September 22 and 23 and widespread rain on September 24, with isolated heavy rainfall over the sub-division on September 23 and 24.
Where the Heavy Rain Warnings Fall Next Week
In the Alipore seven-day chart, the heavy rainfall flags of 7 to 11 cm at one or two places are concentrated in the coastal and south-western districts rather than the city itself:
- South 24 Parganas and East Midnapore: heavy rain very likely on September 23, 24 and 25.
- West Midnapore and Jhargram: heavy rain very likely on September 24 and 25.
- Kolkata, Howrah, Hooghly and North 24 Parganas: light to moderate rain at many places on September 23, rising to most places on September 24 and 25, but no heavy rain warning as of Saturday morning.
Those later-week numbers will be revised daily as the low pressure takes shape, so treat them as a heads-up rather than a fixed plan. The near certainty is that the second half of next week is wetter than the first.
Coastal Advisory: Swell Surge Alert Till Sunday Night
Even without a fishermen warning, there is a sea-state advisory worth knowing if you are heading to Digha, Mandarmani, Bakkhali or the Sundarbans this weekend. INCOIS has forecast swell waves with a long 15 to 19 second period and heights of 0.9 to 1.1 metres along the West Bengal coast up to 11:30 pm on Sunday, September 20. RMC Kolkata’s bulletin notes the possibility of surging waves and advises boats to ply with utmost vigilance and beachgoers to take due care.
What This Means for the Puja Run-Up
Kolkata is now four weeks from Mahalaya on October 10 and less than a month from Maha Shashthi on October 16, and this is the stretch when pandal frames go up, Kumartuli’s idols get their final coats of paint and weekend footfall at Gariahat, New Market and Hatibagan climbs sharply. A wet Saturday and Sunday will slow bamboo work at the bigger pujas and push shoppers into the evening lull after the showers pass. Organisers still finalising their power connections can check our guide to the Durga Puja 2026 power plan and helplines, and anyone whose commute runs through the city’s usual trouble spots will find the flood-prone stretches mapped in our Kolkata Monsoon Commute Survival Guide.
A Sign the Season Is Turning
There is one more line in Friday’s national bulletin that Kolkata will care about eventually: IMD says conditions are becoming favourable for the withdrawal of the southwest monsoon from parts of West Rajasthan around September 19. Withdrawal begins in the far north-west and takes weeks to reach the east, so Bengal’s monsoon is not ending yet. But it is the first formal signal of the season closing, and it usually means the rain that follows comes in bursts tied to Bay of Bengal systems like this one, rather than the steady daily showers of July and August.
Safety Tips for a Thunderstorm Weekend
IMD’s own impact note for the warning districts is short: lightning strikes are the main risk, especially in open ground. A few practical points for the city:
- When a storm builds, get indoors or into a solid structure. Do not wait it out under a tree, a bus shelter with a metal roof or next to an electric pole.
- Stay away from water bodies, including the Maidan lakes, Rabindra Sarobar and the Hooghly ghats, while lightning is active.
- Gusts of 30 to 40 kmph are enough to bring down loose hoardings and half-built pandal frames, so give construction sites a wide berth during a squall.
- If you are riding a two-wheeler, pull over and wait; visibility drops sharply in a Kolkata cloudburst and the first ten minutes of rain leave roads at their slickest.
- Unplug sensitive electronics during close lightning, and keep a torch and a charged power bank handy in case of local outages.
- Check the IMD Kolkata site or the Mausam app before heading to the coast, since the swell surge alert runs through Sunday night.
Frequently Asked Questions
Will it rain in Kolkata today, September 19?
Yes. IMD’s Alipore office forecasts light to moderate rain or thundershowers very likely at many places in Kolkata on Saturday, with thunderstorm, lightning and gusty winds of 30 to 40 kmph very likely at one or two places.
Is the weekend forecast the same for Sunday?
It is. Sunday, September 20, carries the identical forecast and the same thunderstorm warning, valid until 8:30 am on Monday.
Is Kolkata under a red or orange alert?
No. The current warning for Kolkata is for thunderstorm, lightning and gusty winds at one or two places, which sits at the lower end of IMD’s colour scale. There is no heavy rain warning for the city in the Saturday morning bulletin.
Will the Andaman Sea low pressure hit Kolkata?
Not directly, based on the current track. IMD expects it to move west-northwestwards towards the south Odisha and north Andhra Pradesh coasts over three to four days. Bengal is expected to see increased rain on its northern flank around September 23 and 24, with heavy rain flags on South 24 Parganas, East Midnapore, West Midnapore and Jhargram rather than Kolkata.
Is it safe to go to Digha or the Sundarbans this weekend?
There is no fishermen or port warning, but a swell surge alert is in force along the West Bengal coast until 11:30 pm on Sunday. Boats are advised to ply with utmost vigilance and beach recreation should be taken with care.
Which days next week look driest?
Monday, September 21, and Tuesday, September 22, are the lightest days in the outlook for Kolkata, with rain only likely at a few places and no thunderstorm warning.
The Bottom Line
This weekend in Kolkata is a thunderstorm weekend rather than a flood weekend. Expect showers on both days, a couple of sharp squalls with lightning, and muggy heat in between. The Karam Puja long weekend gets a quieter Monday and Tuesday, before a new Bay of Bengal system pulls a wetter spell back over South Bengal from around Wednesday. The low pressure itself is heading for Odisha, not Bengal, but the coastal districts south of the city are the ones to watch. We will update this page as IMD revises its bulletins.
Sources: India Meteorological Department, Regional Meteorological Centre Kolkata, South Bengal seven-day forecast and warnings issued on the morning of 19 September 2026 (mausam.imd.gov.in/kolkata); IMD All India Weather Summary and Forecast Bulletin issued at 8:34 pm on 18 September 2026; INCOIS swell surge advisory as relayed in the RMC Kolkata bulletin. Weekend temperature and humidity figures cross-checked against published media forecasts for 19 September 2026.
Featured image: People with umbrellas walking through a Kolkata street in the rain, photo by Dibakar Roy on Unsplash.
