Chennai has a tropical wet and dry climate (Köppen Aw) with three distinct seasons: hot and humid summer (March to June), monsoon rains (July to November), and mild winter (December to February). The city lies on the Coromandel Coast of the Bay of Bengal, which moderates temperatures slightly but brings heavy northeast monsoon rains from October through December.
Chennai Weather by Month: Temperature and Rainfall Data
Chennai’s climate stays warm year-round. The coolest month is January with an average high of 29°C (84°F) and low of 21°C (70°F). The hottest is May, averaging 37°C (99°F) high and 28°C (82°F) low. The city receives about 1,400mm of rain annually, nearly 60% of which falls during the northeast monsoon from October to December.
Monthly Weather Breakdown for Chennai
| Month | Avg High (°C/°F) | Avg Low (°C/°F) | Rainfall (mm) | Humidity (%) | Sun (hours/day) | Sea Temp (°C) |
|---|---|---|---|---|---|---|
| January | 29 / 84 | 21 / 70 | 27 | 72 | 9 | 26 |
| February | 31 / 88 | 22 / 72 | 7 | 70 | 9 | 27 |
| March | 33 / 91 | 24 / 75 | 5 | 68 | 9 | 28 |
| April | 35 / 95 | 27 / 81 | 15 | 68 | 9 | 30 |
| May | 37 / 99 | 28 / 82 | 45 | 62 | 8 | 30 |
| June | 37 / 99 | 28 / 82 | 65 | 58 | 6 | 29 |
| July | 35 / 95 | 26 / 79 | 110 | 65 | 6 | 29 |
| August | 35 / 95 | 26 / 79 | 130 | 70 | 6 | 28 |
| September | 34 / 93 | 26 / 79 | 125 | 73 | 6 | 29 |
| October | 32 / 90 | 25 / 77 | 260 | 78 | 6 | 29 |
| November | 30 / 86 | 23 / 73 | 340 | 80 | 6 | 28 |
| December | 29 / 84 | 22 / 72 | 160 | 77 | 7 | 27 |
Chennai Rainfall Patterns
Chennai receives most of its rain from the northeast monsoon (October to December), unlike most of India which depends on the southwest monsoon (June to September). November is the wettest month with 340mm of rain, often from cyclonic systems in the Bay of Bengal. The southwest monsoon brings moderate rain from July through September but the city lies in the rain shadow of the Western Ghats, reducing its impact. January through May are dry, with February and March each averaging under 10mm.
Humidity and Comfort Levels in Chennai
Coastal humidity is the main challenge for visitors. Relative humidity ranges from 58% in June to 80% in November. The combination of 35°C+ temperatures and 70%+ humidity from April through October creates a heat index that often exceeds 45°C (113°F). December through February are the most comfortable months with lower humidity and highs under 31°C (88°F). Air conditioning is essential from March through November. The sea breeze, strongest from 2pm to 5pm, provides some relief along Marina Beach and East Coast Road.
