September weather forecast
Haikou, China

The advent of September brings a slight decrease in temperature from the intensity of August's heat, hinting at the approaching season's transition. Despite the cooling trend, the weather in Haikou remains humid and wet, with rainfall maintaining its abundant downpours. It offers an opportunity to witness the turning point from the sweltering summer to cooler, more comfortable temperatures ahead.

Temperature

Haikou observes a minor difference in average high-temperatures between August's 32.3°C (90.1°F) and September's 30.7°C (87.3°F). Haikou records an average nighttime low of 24.6°C (76.3°F) in September.

Heat index

September's mean heat index is calculated to be a scorching 42°C (107.6°F). Preventive measures are required to mitigate the risk of heat cramps and heat exhaustion. Continuous activity may precipitate heatstroke.
One should be cognizant that the heat index values are tailored for shaded spots and mild winds. 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 'felt air temperature' or 'feels like', combines air temperature and relative humidity to represent a human perceived temperature equivalent. Physical activity, clothing, and metabolic variations are additional factors that impact an individual's perception of temperature. When you're directly under the sun's rays, remember that the heat index may surge by 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Young children are more at risk than adults since they tend to sweat less. Moreover, their large skin surface in proportion to their small bodies and the high heat production due to their activities contribute to their vulnerability.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by evaporation of sweat. Greater relative humidity lessens the rate of evaporation, thus decreasing the body's heat dispersal, which gives rise to a sensation of overheating. Overheating can ensue when the body accumulates more heat than it can release, and dehydration severity may vary.

Humidity

The average relative humidity in September is 85%.

Rainfall

The month with the most rainfall in Haikou is September, when the rain falls for 14.3 days and typically aggregates up to 244mm (9.61") of precipitation.

Sea temperature

In Haikou, the average seawater temperature in September is 28.4°C (83.1°F).
Note: For swimming, diving, and similar activities, the water temperatures between 25°C (77°F) and 29°C (84.2°F) are considered delightful, allowing for extended periods of enjoyment without discomfort.

Daylight

The average length of the day in September is 12h and 16min.
On the first day of the month, sunrise is at 06:23 and sunset at 18:54. On the last day of September, sunrise is at 06:29 and sunset at 18:28 CST.

Sunshine

The average sunshine in September in Haikou is 6.5h.

UV index

The months with the highest UV index are March 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 unsafe exposure to UV radiation for the average person.
Note: A maximum high UV index of 12 in September translates into the following recommendations:
Employ all crucial safeguards, unprotected skin could burn rapidly. Remember that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. Make an effort to avoid direct sun exposure during these hours. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly. Apply generously and frequently reapply a sunscreen with SPF 30 or more even on cloudy days, particularly after a swim or outdoor exercise. Stay cautious! Sand and water reflections increase UV radiation potency.