Chennai weather by month — averages, rainfall & climate trends
Unlike most of India, Chennai gets its rain at the tail end of the year, when the retreating northeast monsoon and the cyclones of the Bay of Bengal sweep in off the sea. 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 Chennai, India.
Today vs average
+2.2°Cwarmer than usual
How it’s changed
Right now
What it's doing today vs the historical average for this date.
Right now
28.0°
35°27°37°27°38°27°34°27°35°27°37°27°36°27°On this date — July 19
Warmer than usual · 2.2°C above the average high
- Record high: 35.8° · 1957
- Record low: 24.4° · 1943
- One year ago: 32.1°
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 Chennai is sampled from the ECMWF ERA5 reanalysis at 13.09°N, 80.28°E, with daily records since 1940.
- Coordinates
- 13.09°N, 80.28°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: +1.2°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
Chennai lies on the flat southeastern coast of India, on the shore of the Bay of Bengal. Its tropical climate (Köppen As, with a dry summer) sets it apart from most of the country: rather than relying on the June-to-September southwest monsoon that waters the rest of India, Chennai draws the bulk of its rain from the northeast monsoon between October and December. The long lead-up to it is hot and humid, with the fiercest heat from April to June.
That late-year rainy season is also the dangerous one. Cyclones and tropical depressions spinning out of the Bay of Bengal regularly come ashore, and the low, flat coast floods easily. Still fresh in memory is the catastrophic flooding of 2015, with further serious flooding in 2023, both made worse by lost wetlands and overwhelmed drainage in a fast-growing city.
The year peaks in May, at 30.7°C over the day and around 34.3°C by mid-afternoon. At the other extreme, January averages 24.6°C, with typical overnight lows of 22.3°C.
In total, Chennai averages about 995 mm of precipitation a year; November is usually the wettest month (232 mm) and February the driest (11 mm).
Comparing the record's first decade with its most recent one, Chennai now averages 0.9°C warmer than it did in the 1940s. The last decade has also run wetter, about 19% above the long-term precipitation average.
Climate graph (climograph)
May is the warmest month, January the coolest — a yearly swing of 6°C. Wettest month: November (~232 mm). Whole year averages ~995 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.
Chennai 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 | 27.2° | 22.3° | 28 mm | 11.3 h | 29.9° (1991) | 17.8° (1990) |
| February | 28.7° | 22.9° | 11 mm | 11.6 h | 33.7° (1950) | 17.8° (1989) |
| March | 30.8° | 24.7° | 16 mm | 11.9 h | 37.3° (1953) | 20.4° (1989) |
| April | 32.6° | 27.0° | 18 mm | 12.3 h | 38.5° (1941) | 22.8° (1993) |
| May | 34.3° | 28.3° | 40 mm | 12.6 h | 39.4° (1964) | 24.7° (1995) |
| June | 34.1° | 28.1° | 53 mm | 12.8 h | 37.9° (1972) | 24.8° (1996) |
| July | 33.1° | 27.2° | 74 mm | 12.7 h | 36.8° (1980) | 24.2° (1943) |
| August | 32.4° | 26.8° | 96 mm | 12.4 h | 36.5° (2014) | 24.2° (1965) |
| September | 31.7° | 26.4° | 107 mm | 12.1 h | 36.5° (1951) | 23.5° (1964) |
| October | 29.9° | 25.4° | 196 mm | 11.7 h | 34.8° (1952) | 21.3° (1980) |
| November | 28.1° | 24.2° | 232 mm | 11.4 h | 33.9° (1952) | 20.4° (1991) |
| December | 27.0° | 23.0° | 123 mm | 11.2 h | 31.3° (1950) | 17.3° (1941) |
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: +0.11°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
Dec–Feb is warming fastest: +0.14°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: 215.5 early in the record → 237.6 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 1964, all-time low in 1941: 39.4°C / 17.3°C.
One point per year — the single hottest and coldest day recorded that year.
Annual rainfall
~995 mm/year on average. Last decade ran +19% vs that average. Long-term trend: +25 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).