Kolkata weather by month — averages, rainfall & climate trends
Kolkata sits deep in the Ganges delta, hot and steaming for much of the year until the monsoon breaks, with violent pre-monsoon squalls and Bay of Bengal cyclones bracketing the wet season. Average temperatures and rainfall by month, a climate graph, today's conditions versus the long-term average, and how the climate has shifted since 1940 — all on one page for Kolkata, India.
Today vs average
+0.5°Cabout average
How it’s changed
Right now
What it's doing today vs the historical average for this date.
Right now
27.4°
32°27°31°27°30°26°28°26°
29°26°28°25°29°26°On this date — July 19
About average
- Record high: 34.9° · 2018
- Record low: 24.7° · 1975
- One year ago: 33.3°
Every July 19 in history — coldest to hottest
Dots show daily highs (top) and lows (bottom) for each July 19 on record (n = 87). Outlined dots are today's forecast.
Area we sample
Each city's history comes from one ERA5 grid cell — about 28 km across, shown by the dashed box. Near mountains or coasts, conditions can vary across the cell.
Location & data
Historical weather for Kolkata is sampled from the ECMWF ERA5 reanalysis at 22.56°N, 88.36°E, with daily records since 1940.
- Coordinates
- 22.56°N, 88.36°E
- Time zone
- Asia/Kolkata
- Period
- 1940–2026
- Data source
- ERA5 (ECMWF)
Last 30 days
25 of the last 31 days were warmer than the historical average for that date. Average difference: +0.6°C.
Each bar is one day, from morning low to afternoon high. Warm-colored bars are days whose mean ran above average; cool bars ran below. The dot inside the bar is the daily mean. The shaded band is the typical 10–90% range expected for that date. Average = the day's mean temperature averaged across every year of record (1940–2026) for that calendar date.
This date over the years
One dot per year — the mean temperature on this calendar date. Dots are warmer or cooler than the long-term average (dashed line); the shaded band is the typical 10–90% range, and the highlighted dot is today's forecast. Based on ERA5 reanalysis — modelled estimates, not station readings.
Weather by month
Average temperatures and rainfall for each month — what a typical year looks like, from the full record.Climate overview
Kolkata stands in the lower Ganges delta of eastern India, a short distance from the border with Bangladesh. Its tropical wet-and-dry climate (Köppen Aw) brings hot, sticky summers from March to June and a brief, mild winter of a couple of months. Most of the year's rain comes with the southwest monsoon between June and September, when the delta turns humid and waterlogged.
The run-up to the monsoon has a drama of its own: fierce afternoon squalls known as kal baishakhi, or Nor'westers, that roll in with sudden rain, dust and hail and a welcome break from the heat. The delta also lies squarely in the path of Bay of Bengal cyclones, which have struck devastatingly over the centuries and as recently as Cyclone Amphan in 2020.
May brings the year's peak warmth: daily means of 30.4°C, with afternoons typically reaching 35.2°C. At the other extreme, January averages 19.1°C, with typical overnight lows of 13.6°C.
Kolkata picks up roughly 1654 mm a year, with a peak of 348 mm in July and as little as 13 mm in December. A typical year brings rain or snow on around 165 days.
The record here starts in 1940, and since then the annual mean in Kolkata has climbed 0.9°C from the first ten years to the last ten. The year-by-year charts above trace that shift in detail.
Climate graph (climograph)
May is the warmest month, January the coolest — a yearly swing of 11°C. Wettest month: July (~348 mm). Whole year averages ~1654 mm of rain.
Bars = average monthly rainfall (right axis). Lines = average daily high and low (left axis). Average = each month's value averaged across every year of record (1940–2026).
Monthly wind
Average daily peak wind at 10 m, by month.
Monthly solar energy
Average daily incoming solar energy in megajoules per square metre — a measured proxy for how sunny the month is.
Kolkata month by month — what to expect
Typical conditions for each month, averaged across the full record (since 1940). Daylight is the time from sunrise to sunset. Record high/low are the most extreme values in the ERA5 dataset (modelled since 1940), so they can differ from official weather-station readings.
| Month | Avg high | Avg low | Rain | Daylight | Record high | Record low |
|---|---|---|---|---|---|---|
| January | 25.9° | 13.6° | 14 mm | 10.8 h | 32.3° (1946) | 7.7° (2013) |
| February | 29.0° | 16.7° | 26 mm | 11.2 h | 36.9° (1942) | 8.7° (1974) |
| March | 33.4° | 21.6° | 42 mm | 11.8 h | 41.9° (1955) | 13.0° (1979) |
| April | 35.6° | 25.3° | 76 mm | 12.5 h | 44.0° (1954) | 17.5° (1990) |
| May | 35.2° | 26.8° | 129 mm | 13.1 h | 45.0° (1957) | 21.4° (1987) |
| June | 33.2° | 27.1° | 262 mm | 13.4 h | 44.5° (1945) | 22.6° (1961) |
| July | 31.3° | 26.5° | 348 mm | 13.3 h | 37.6° (1982) | 24.0° (1981) |
| August | 31.2° | 26.3° | 319 mm | 12.8 h | 36.1° (2011) | 23.3° (1976) |
| September | 31.1° | 25.8° | 257 mm | 12.1 h | 36.3° (2015) | 22.2° (1940) |
| October | 30.5° | 23.6° | 132 mm | 11.5 h | 35.7° (2018) | 15.7° (1954) |
| November | 28.6° | 18.6° | 34 mm | 10.9 h | 33.7° (2009) | 11.6° (1943) |
| December | 26.2° | 14.4° | 13 mm | 10.6 h | 31.5° (1944) | 8.4° (1966) |
How it has changed
Year-by-year signals from 1940 to today.Climate stripes
Annual mean shifted from 1940–1949 to 2016–2025 by +0.9°C.
Each vertical stripe is one year. Color encodes how much that year's annual mean differed from the long-term average. Average = each year's annual mean compared to the average of all years (1940–2026). cooler ← → warmer
Annual mean temperature
Long-term trend: +0.10°C per decade.
One point per year — the temperature averaged across the whole year. The dashed line is the least-squares long-term trend. Based on ERA5 reanalysis — modelled estimates, not station readings.
Seasonal warming
Sep–Nov is warming fastest: +0.24°C per decade.
Each faint line is one three-month period's average per year; the bold dashed line is its long-term trend. Different parts of the year often warm at different rates. Based on ERA5 reanalysis — modelled estimates, not station readings.
Hot days vs frost days
Days ≥ 30°C per year: 201.2 early in the record → 249.1 recently. Frost days: 0 → 0.
Thin lines are raw yearly counts; thick lines are the smoothed trend that removes year-to-year noise. The hot-day threshold is auto-picked per city so the line actually moves. Average = a centered 5-year rolling average to smooth weather noise.
Yearly hot & cold extremes
All-time high in 1957, all-time low in 2013: 45.0°C / 7.7°C.
One point per year — the single hottest and coldest day recorded that year.
Annual rainfall
~1654 mm/year on average. Last decade ran +4% vs that average. Long-term trend: −13 mm per decade.
One bar per year of total rainfall. Dashed line is the long-term average. Average = the average annual rainfall across every year of record (1940–2026).
Day-by-day grid
Each tiny square is one calendar day across the full record — ~30,000 days per city. Use the mode switch above the chart: Anomaly colors each day by how far it ran from the historical average for that date (red = warmer, blue = cooler), Daily mean temp shows the absolute mean temperature for the day (useful to see seasons and heatwaves), and Precipitation shows daily rainfall (useful to spot wet/dry seasons and droughts). Average = the long-term average for that calendar date (1940–2026).