September weather forecast
Happy Valley, Hong Kong

During September, Happy Valley begins to bid farewell to summer with a gradual reduction in temperature. The drop offers a slight comfort from the high humidity levels experienced over the past few months. The city continues to enjoy long hours of sunshine, favourable for outdoor activities. October promises a greater relief with a further decrease in rainfall and temperature. Notably, September experiences a marginal drop in average wind speed to 13.5km/h (8.4mph), contributing to the easing weather conditions.

Temperature

The transition from August to September sees an average high-temperature of a warm 29.6°C (85.3°F), indicating a minor variance from the prior month. Happy Valley, during the nights of September, averages a temperature close to its daytime high, at a still moderately hot 26.5°C (79.7°F).

Heat index

In September, the heat index is computed to be a sweltering 36°C (96.8°F). Ensure heightened precautions, risk of heat cramps and heat exhaustion is significant. Sustained activity could provoke heatstroke.
Thinking about the heat index, one should account for its values in shaded areas with gentle breezes. Heat index values may rise by up to 15 Fahrenheit (8 Celsius) degrees when exposed to direct sunlight.
Note: The heat index, also known as 'feels like' or 'apparent temperature', is a composite of temperature and humidity figures to convey how warm it feels. One's perception of temperature is subjective, varying based on their activity and individual heat perception, influenced by factors like wind, clothing, and metabolic variations. Being under direct sunshine can magnify the heat experience, possibly pushing up the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite important for babies and toddlers. Young individuals usually face greater risks than adults as their sweat production is less. Also, their larger skin surface relative to their small bodies and the high heat generation due to their activity contributes to their vulnerability.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by evaporation of sweat. When there is abundant moisture in the air, the body's cooling through the evaporation process becomes less effective, leading to the sensation of overheating. The body is at risk of dehydration and related complications when it fails to shed excessive heat.

Humidity

The average relative humidity in September is 77%.

Rainfall

In Happy Valley, during September, the rain falls for 22.7 days and regularly aggregates up to 155mm (6.1") of precipitation. In Happy Valley, during the entire year, the rain falls for 224.5 days and collects up to 1264mm (49.76") of precipitation.

Daylight

In September, the average length of the day is 12h and 17min.
On the first day of the month, sunrise is at 06:06 and sunset at 18:40. On the last day of September, in Happy Valley, sunrise is at 06:14 and sunset at 18:11 HKT.

Sunshine

In Happy Valley, the average sunshine in September is 8.4h.

UV index

May through September, with an average maximum UV index of 7, are months with the highest UV index. A UV Index value of 6 to 7 symbolizes a high health hazard from unsafe exposure to UV radiation for average individuals.
Note: In September, a daily maximum UV index of 7 leads to the following instructions:
Incorporate safeguards and honour sun safety principles. Protection from skin and eye damage is obligatory. UV radiation from the sun is at its strongest between 10 a.m. and 4 p.m. Try to limit direct exposure during these hours. Boost your sun resistance with garments that are densely woven yet spacious.