September weather forecast and climate
Shanghai, China

September, the first month of the autumn, in Shanghai, is also a moderately hot month, with average temperature varying between 27.9°C (82.2°F) and 22.4°C (72.3°F).

Temperature

In Shanghai, the average high-temperature in September marginally drops, from a hot 31.5°C (88.7°F) in August, to a moderately hot 27.9°C (82.2°F). In September, the average low-temperature is 22.4°C (72.3°F).

Heat index

In September, the average heat index is calculated to be a hot 31.1°C (88°F). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.
Take into consideration that the heat index values are calculated for shade and light wind conditions. With 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', 'felt air temperature', 'apparent temperature', or 'real feel', is a measure of how hot it feels when the actual air humidity is factored in. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (clothing, metabolic differences, wind). Be aware that direct exposure to sunlight increases heat impact and may raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

In September, the average relative humidity in Shanghai is 75%.

Rainfall

In Shanghai, in September, it is raining for 9.1 days, with typically 87.1mm (3.43") of accumulated precipitation. Throughout the year, there are 120.8 rainfall days, and 1166.1mm (45.91") of precipitation is accumulated.

Sea temperature

In September, the average sea temperature in Shanghai is 25°C (77°F).
Note: 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.

Daylight

In September, the average length of the day is 12.4h.

Sunshine

In Shanghai, the average sunshine in September is 5.6h.

UV index

In Shanghai, the average daily maximum UV index is 9. A UV Index reading of 8 to 10 represents a very high health risk from the exposure to the Sun's UV rays for ordinary individuals.
Note: The average daily UV index of 9 transform into the following instructions:
Take special precautions, as unprotected skin can be damaged and can burn quickly. 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. 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. 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. Beware! The strength of the UV rays is significantly increased by the reflection of the water and sand.