September weather forecast
Chiang Mai, Thailand

September continues the monsoon trend with high humidity and substantial rain. The rainfall begins to slightly decrease with 211mm (8.31") registering over 20 days. The daylight hours reduce to 12.2, and temperatures remain relatively stable compared to August. Despite the continuing rainfall, Chiang Mai retains its mesmerising appeal in September.

Temperature

Chiang Mai observes an average high-temperature of a still tropical 31.7°C (89.1°F) in September, barely different from 31.5°C (88.7°F) in August. Chiang Mai experiences a mean temperature of 23.2°C (73.8°F) during September nights.

Heat index

In September, the heat index is evaluated at an extremely hot 44°C (111.2°F). Careful: Heat exhaustion and heat cramps are anticipated. With ongoing exertion, heatstroke becomes a possibility.
Heat index values are typically calculated for conditions of shade and a light breeze. A direct sunlight exposure may boost the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'felt air temperature', evaluates the perceived heat by adding the effect of moisture in the air. The effect of weather is individual, with a variety of people experiencing it differently due to distinctions in body mass, height, and level of activity. The sun, when shining directly, can have a significant impact on the perceived temperature, increasing the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially vital to children. Youngsters generally face more threats than adults given their lesser ability to sweat. Coupled with their larger skin surface relative to their small bodies and higher heat production due to their activities, they are more endangered.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by evaporation of sweat. Excessive relative humidity disturbs the body's typical cooling process by reducing evaporation, leading to a decrease in body cooling rate and an increase in the sensation of warmth. When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat-related illnesses and disorders may develop.

Humidity

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

Rainfall

In Chiang Mai, in September, it is raining for 20 days, with typically 211mm (8.31") of accumulated precipitation. In Chiang Mai, Thailand, during the entire year, the rain falls for 113 days and collects up to 1131mm (44.53") of precipitation.

Daylight

In September, the average length of the day is 12h and 15min.
On the first day of September in Chiang Mai, sunrise is at 06:09 and sunset at 18:38. On the last day of the month, sunrise is at 06:14 and sunset at 18:13 +07.

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 in Chiang Mai. A UV Index estimate of 11, and higher, represents an excessive health risk from exposure to the Sun's UV radiation for the ordinary person.
Note: In September, an average UV index of 12 transforms into the following instructions:
Adopt all essential precautions. Preventing sun harm is crucial. Limit direct sun exposure especially between 10 a.m. and 4 p.m., when UV radiation is at its peak. However, keep in mind that shade structures may not provide full sun protection. Employ a wide-brim hat for potent defense against up to 50% of UV rays. Use liberally and reapply a broad-spectrum SPF 30+ sunscreen every two hours, or straight away after any outdoor workout or swim.