Chiang Mai
Thailand
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Chiang Mai, Thailand

The stunning aerial panorama of the fantastic Two Pagoda on top of the Doi Inthanon mountain in Chiang Mai, Thailand
The stunning aerial panorama of the fantastic Two Pagoda on top of the Doi Inthanon mountain in Chiang Mai, Thailand
The first month of the autumn, September, is also a hot month in Chiang Mai, Thailand, with average temperature ranging between max 31.7°C (89.1°F) and min 23.2°C (73.8°F).

Temperature

In Chiang Mai, the average high-temperature is relatively the same as in August - a still hot 31.7°C (89.1°F). In Chiang Mai, the average low-temperature is 23.2°C (73.8°F).

Heat index

In September, the average heat index is estimated at an extremely hot 43.7°C (110.7°F). Beware - heat cramps and heat exhaustion are very likely. Heatstroke is imminent with prolonged activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. 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 'feels like', 'real feel', 'apparent temperature', or 'felt air temperature', 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 (metabolic differences, pregnancy, differences in body mass, height, and shape). Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. 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. High relative humidity reduces the evaporation rate, resulting in a lower heat removal rate from the body, causing the perception of being overheated. When heat gain surpasses the level the body can shed, body temperature begins to increase, and consequently, overheating and dehydration can occur, with varying severity.

Humidity

August and September, with an average relative humidity of 81%, are most humid months.

Rainfall

In Chiang Mai, during September, the rain falls for 20 days and regularly aggregates up to 211.4mm (8.3") of precipitation. In Chiang Mai, during the entire year, the rain falls for 113 days and collects up to 1130.6mm (44.5") of precipitation.

Daylight

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

Sunshine

August and September, with an average of 5.2h of sunshine, are months with the least sunshine in Chiang Mai.

UV index

March through September, with an average maximum UV index of 12, are months with the highest UV index. A UV Index estimate of 11, and higher, represents an excessive health risk 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:
Practice all essential precautions. Protection against sun damage is crucial. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise.

What is the temperature in September in Chiang Mai?

The average high-temperature, in September, in Chiang Mai, Thailand, is 31.7°C (89.1°F), while the average low-temperature is 23.2°C (73.8°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 43.7°C (110.7°F).

What are the most humid months in Chiang Mai?

Months with the highest humidity in Chiang Mai, Thailand, are August and September, with an average relative humidity of 81%.

What is the average humidity in September in Chiang Mai?

In Chiang Mai, Thailand, the average relative humidity in September is 81%.

How much does it rain in Chiang Mai in September?

In Chiang Mai, in September, it is raining for 20 days, with typically 211.4mm (8.3") of accumulated precipitation.

What is the average length of the day in September in Chiang Mai?

The average length of the day in September is 12.2h.

What is the month with the least sunshine in Chiang Mai?

Months with the least sunshine in Chiang Mai are August and September, with an average of 5.2h of sunshine.

How many hours of sunshine does Chiang Mai have in September?

In Chiang Mai, the average sunshine in September is 5.2h.

When is the highest UV index in Chiang Mai?

Months with the highest UV index in Chiang Mai, Thailand, are March through September, with an average maximum UV index of 12.

How high is the UV index in September in Chiang Mai?

The average daily maximum UV index in September is 12. A UV Index reading of 11, and higher, represents an excessive health risk from unsafe exposure to the Sun's UV rays.
Average temperature in September - Chiang Mai, Thailand
  • Average high temperature in September: 31.7°C

The warmest month (with the highest average high temperature) is April (36.5°C).
The month with the lowest average high temperature is December (28.6°C).

  • Average low temperature in September: 23.2°C

The month with the highest average low temperature is June (24°C).
The coldest month (with the lowest average low temperature) is January (14.9°C).

Average humidity in September - Chiang Mai, Thailand
  • Average humidity in September: 81%

Months with the highest relative humidity are August and September (81%).
The month with the lowest relative humidity is March (52%).

Average rainfall in September - Chiang Mai, Thailand
  • Average rainfall in September: 211.4mm

The wettest month (with the highest rainfall) is August (216.9mm).
The driest month (with the lowest rainfall) is January (4.2mm).

Average rainfall days in September - Chiang Mai, Thailand
  • Average rainfall days in September: 20 days

The month with the highest number of rainy days is September (20 days).
Months with the lowest number of rainy days are January and December (1 days).

Average daylight in September / Average sunshine in September - Chiang Mai, Thailand
  • Average daylight in September: 12.2h

The month with the longest days is June (Average daylight: 13.3h).
The month with shortest days is December (Average daylight: 11h).

  • Average sunshine in September: 5.2h

The month with most sunshine is February (Average sunshine: 9h).
Months with least sunshine are August and September (Average sunshine: 5.2).

Average UV index in September - Chiang Mai, Thailand
  • Average UV index in September: 12

Months with the highest UV index are March, April, May, June, July, August and September (UV index 12).
The month with the lowest UV index is December (UV index 8).