Mumbai is warm all year, and its weather is defined by one dramatic event: the southwest monsoon, which delivers nearly all of the year's rain between June and September. Its clock is India Standard Time, a half-hour offset that the whole country shares and that never changes for daylight saving.
Climate overview
Mumbai sits on a peninsula on India's west coast, facing the Arabian Sea. Its climate is tropical monsoon (Köppen Am), sometimes given as tropical wet and dry (Aw), and the sea keeps temperatures within a narrow band. Average highs only range from 30°C to 34°C through the year, and the annual mean temperature is 28°C. Nights are where the seasons show: average lows fall to 17°C in January and rise to 27°C in May.
Rain is the real story. Mumbai receives about 2,502 mm a year, and the four monsoon months bring almost all of it, at 384–920 mm each. July alone averages 920 mm. The rest of the year is close to dry. Sunshine follows the same pattern in reverse, from 273 hours in May down to 61 in July, the heart of the monsoon.
- Mumbai
Show the numbers
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mumbai | 0.2 | 0.2 | 0.1 | 0.1 | 7.3 | 526 | 920 | 561 | 384 | 91 | 11 | 1.6 |
Mumbai through the seasons
Winter (December to February)
This is Mumbai's most pleasant season. Highs stay at 31–33°C, but nights cool to 17–18°C, the air is drier and skies are mostly clear. Evenings along Marine Drive and the seafront promenades are at their most comfortable. Air quality can be poor on still winter days, when haze settles over the city.
Pre-monsoon (March to May)
Heat and humidity build steadily. Highs reach 33–34°C, and with nights climbing to 27°C in May there is little relief after dark. The heavy, sticky air makes it feel much hotter than the thermometer shows. Occasional pre-monsoon showers may arrive in late May, often with thunder.
Monsoon (June to September)
The southwest monsoon usually arrives in the first half of June and brings frequent, often torrential rain, with July the wettest month at 920 mm. Cloud and rain bring daytime highs down slightly, to 30–33°C. Waterlogging and local flooding can disrupt trains and roads, but the city turns green and the hills around it fill with waterfalls.
Post-monsoon (October and November)
The rain fades during October, and a hot, humid spell known locally as "October heat" follows. Daytime highs in October and November reach 34°C, the highest of the year, because the clouds have cleared but the air is still moist. By late November the air becomes drier and the winter season begins.
What makes Mumbai's weather distinctive
The arrival of the monsoon is a major event in Mumbai, watched for in the news and celebrated when the first heavy rain breaks the pre-monsoon heat. Then comes the hard part. On the heaviest days, rain can flood low-lying areas, suspend suburban train services and bring the city to a halt, and authorities may advise people to stay at home.
The sea makes it worse. When a high tide coincides with heavy rain, water has nowhere to drain, and flooding can last for hours. The coastline sees rough seas throughout the monsoon, and swimming at the city's beaches is dangerous in these months.
Best time to visit Mumbai
November to February is the best time to visit Mumbai, with warm days, cooler evenings and almost no rain. December and January are the most comfortable months of all. The monsoon months offer a dramatic, green and atmospheric city, but heavy rain can disrupt travel plans at short notice, so build in flexibility. April and May are hot and humid, and the post-monsoon weeks of October can be just as sticky.
What to pack
- Light cotton or linen clothing that dries quickly
- A sturdy umbrella, a light rain jacket and waterproof sandals for the monsoon
- A light layer for air-conditioned trains, offices and restaurants
- Sunscreen and sunglasses year-round
- Modest clothing (covered shoulders and knees) for temples, mosques and other religious sites
Time in Mumbai
Mumbai uses the Asia/Kolkata time zone, India Standard Time, and is on UTC+5:30 all year. India does not observe daylight saving time, and the whole country, from Gujarat in the west to Arunachal Pradesh in the east, runs on a single clock.
Living on Mumbai time
India Standard Time is measured from the 82.5° East meridian near Mirzapur in Uttar Pradesh, which falls halfway between the meridians for whole-hour offsets; that is where the half hour comes from. Mumbai sits at about 72.9° East, nearly ten degrees west of that line, so the sun rises and sets about 38 minutes later than it would on the reference meridian. That is why winter sunrises come as late as 07:06 and summer sunsets as late as 19:18.
Mumbai held on to its own time longer than any other Indian city. "Bombay Time", about 4 hours 51 minutes ahead of Greenwich, was used locally from the late 19th century, and the city kept it even after India Standard Time was introduced in 1906, only switching fully in 1955.
A single zone for a country this wide is a compromise. In the north-east the sun can rise nearly two hours earlier than in Gujarat, and tea gardens in Assam traditionally ran on their own "chaibagan time", one hour ahead of IST. Proposals for a second time zone are studied from time to time but have not been adopted. Our post on the world's fractional time zones explains why a few countries run on half-hour and 45-minute offsets.
Major festivals such as Ganesh Chaturthi and Diwali follow the Hindu lunisolar calendar, so their dates move each year, usually somewhere between August and November. Check the dates before planning business travel, as offices and traffic are affected.
Scheduling with Mumbai
Because India never changes its clocks, any change in the gap with Mumbai comes from the other city. Right now Mumbai is 5 hours 30 minutes ahead of London, 10 hours 30 minutes ahead of New York and 1 hour 30 minutes ahead of Dubai. The Gulf overlap covers almost the whole working day, and the Mumbai afternoon meets the European morning. New York is the stretch: only the Mumbai evening reaches the start of the New York day. The half-hour offset means meeting slots often land on the half hour, so make sure calendar invites show :30, not a rounded hour.
| With | Difference | Time in Mumbai | Their time |
|---|---|---|---|
| London | −5 h 30 min | 14:30–18:00 | 09:00–12:30 |
| New York | −10 h 30 min | No overlap | – |
| Dubai | −1 h 30 min | 10:30–18:00 | 09:00–16:30 |
| Tokyo | +3 h 30 min | 09:00–14:30 | 12:30–18:00 |
| Sydney | +5 h 30 min | 09:00–12:30 | 14:30–18:00 |
| Date | Sunrise | Sunset | Day length |
|---|---|---|---|
| 20 March | 06:42 | 18:49 | 12 h 6 min |
| 21 June | 06:01 | 19:18 | 13 h 16 min |
| 22 September | 06:27 | 18:35 | 12 h 7 min |
| 21 December | 07:06 | 18:05 | 10 h 59 min |
Frequently asked questions
When is the monsoon in Mumbai?
The southwest monsoon typically arrives in the first half of June and lasts until late September or early October, bringing almost all of the year's rain.
What is the wettest month in Mumbai?
July, with about 920 mm of rain on average, more than many European cities receive in a whole year.
Is Mumbai hot in winter?
Winter days are still warm, at 31–33°C, but nights cool to 17–18°C and the air is drier, so it feels much more comfortable than the rest of the year.
Why does India use a half-hour offset?
India Standard Time is based on the 82.5° East meridian, close to the country's centre, which falls halfway between the meridians for UTC+5 and UTC+6.
Does Mumbai observe daylight saving time?
No. India does not use daylight saving time, so Mumbai stays on UTC+5:30 all year.