Chennai
India
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Chennai, India

A staircase to the front entrance of the Ramakrishna Temple in Chennai, India
A staircase to the front entrance of the Ramakrishna Temple in Chennai, India
The last month of the rainy (monsoon) season, September, is another tropical month in Chennai, India, with average temperature varying between 25.5°C (77.9°F) and 33.9°C (93°F).

Temperature

In September, the average high-temperature is relatively the same as in August - a still tropical 33.9°C (93°F). In September, in Chennai, the average low-temperature is 25.5°C (77.9°F).

Heat index

The average heat index in September is calculated to a blazing hot 47.4°C (117.3°F). Be wary - heat exhaustion and heat cramps are highly anticipated. With continued activity, heatstroke is very likely.
Note that heat index values are valued for light wind and location in the shade. With the exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel', 'apparent temperature', 'felt air temperature', or 'feels like', is an index that combines air temperature and relative humidity to determine the human-perceived temperature equivalent. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (pregnancy, wind, differences in body mass, height, and shape). Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
The human body normally cools itself by perspiration, as evaporated sweat carries heat away from the body. With a lot of moisture in the air, the evaporation process is not as effective, and the body does not cool down as efficiently, creating a perception of overheating. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 37.5°C (99.5°F) to 38.3°C (100.9°F), thermal conditions are potentially life-threatening.

Humidity

In Chennai, India, the average relative humidity is 72%.

Rainfall

In Chennai, India, in September, it is raining for 7.1 days, with typically 137.3mm (5.4") of accumulated precipitation. In Chennai, during the entire year, the rain falls for 59.1 days and collects up to 1391.5mm (54.8") of precipitation.

Sea temperature

In September, the average sea temperature in Chennai is 29.3°C (84.7°F).
Note: For any water activity, surface water temperatures between 25°C (77°F) and 29°C (84.2°F) are considered as excellent and extremely pleasant for lengthened periods.

Daylight

In September, the average length of the day in Chennai, India, is 12.2h.

Sunshine

In Chennai, the average sunshine is 6.6h.

UV index

Months with the highest UV index in Chennai are February through September, with an average maximum UV index of 12. A UV Index value of 11, and more, symbolizes an extreme threat to health from the exposure to the Sun's UV rays for average individuals.
Note: The average daily UV index of 12 in September transform into the following instructions:
Take all necessary precautions, as unprotected skin can burn in minutes. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. A broad-spectrum sunscreen of SPF 30+ should be liberally applied and re-applied every two hours, and immediately after an outdoor workout or a swim. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.

What is the temperature in September in Chennai?

In September, in Chennai, India, the average high-temperature is 33.9°C (93°F), and the average low-temperature is 25.5°C (77.9°F). The average heat index (a.k.a. 'feels like', 'felt air temperature'), that factores the actual air temperature with the relative humidity, in September is evaluated at 47.4°C (117.3°F).

What is the average humidity in September in Chennai?

In Chennai, India, the average relative humidity in September is 72%.

How much does it rain in Chennai in September?

In Chennai, India, in September, it is raining for 7.1 days, with typically 137.3mm (5.4") of accumulated precipitation.

How warm is the water in September in Chennai?

In Chennai, India, in September, the average water temperature is 29.3°C (84.7°F). Water temperature between 25°C (77°F) and 29°C (84.2°F) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

How many hours of daylight does Chennai have in September?

In September, the average length of the day is 12.2h.

How long on average sun shines in September in Chennai?

The average sunshine in September in Chennai is 6.6h.

What is the month with the highest UV index in Chennai?

Months with the highest UV index are February through September, with an average maximum UV index of 12.

What is the UV index reading in September in Chennai?

In Chennai, the average daily maximum UV index in September is 12. A UV Index value of 11, and more, symbolizes an excessive health risk from the exposure to the Sun's UV radiation.
Average temperature in September - Chennai, India
  • Average high temperature in September: 33.9°C

The warmest month (with the highest average high temperature) is June (36.9°C).
The month with the lowest average high temperature is December (28.5°C).

  • Average low temperature in September: 25.5°C

The month with the highest average low temperature is May (27.9°C).
The coldest month (with the lowest average low temperature) is January (20.9°C).

Average humidity in September - Chennai, India
  • Average humidity in September: 72%

The month with the highest relative humidity is November (78%).
The month with the lowest relative humidity is June (57%).

Average rainfall in September - Chennai, India
  • Average rainfall in September: 137.3mm

The wettest month (with the highest rainfall) is November (407.4mm).
The driest month (with the lowest rainfall) is February (2.2mm).

Average rainfall days in September - Chennai, India
  • Average rainfall days in September: 7.1 days

The month with the highest number of rainy days is November (11.7 days).
The month with the lowest number of rainy days is March (0.3 days).

Average sea temperature in September - Chennai, India
  • Average sea temperature in September: 29.3°C

The best month for swimming (with the highest average sea temperature) is May (29.5°C).
The coldest month (with the lowest average sea temperature) is January (26.8°C).

Average daylight in September / Average sunshine in September - Chennai, India
  • Average daylight in September: 12.2h

The month with the longest days is June (Average daylight: 12.9h).
The month with shortest days is December (Average daylight: 11.4h).

  • Average sunshine in September: 6.6h

The month with most sunshine is April (Average sunshine: 9.7h).
The month with least sunshine is July (Average sunshine: 6h).

Average UV index in September - Chennai, India
  • Average UV index in September: 12

Months with the highest UV index are February, March, April, May, June, July, August and September (UV index 12).
The month with the lowest UV index is December (UV index 9).