September weather forecast
Ha Long, Vietnam

September in Ha Long manifests the gradual transition from summer to autumn. Though the rainfall starts to recede to 232mm (9.13"), the level remains significant compared to the rest of the year. The decrease of rainfall does not compromise the charm of Ha Long. With cooling temperatures and a slightly reduced rainfall, September leans gradually towards a more comfortable climate. The changing colors of the city's natural landscape provide an enchanting backdrop for explorers.

Temperature

September in Ha Long is marked by an average high-temperature of a still tropical 30.9°C (87.6°F), almost identical to the preceding month. Ha Long experiences a steady low-temperature of 23.3°C (73.9°F) throughout September.

Heat index

The heat index in September is appraised at an extremely hot 42°C (107.6°F). Ensure heightened precautions, risk of heat cramps and heat exhaustion is significant. Sustained activity could provoke heatstroke.
Remember that heat index calculations are made for conditions in the shade with light wind. Exposure to unobstructed sunshine could lead to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', is what the temperature feels like to the human body when the air temperature is combined with the relative humidity. One's weather perception can be influenced by a range of factors including metabolic differences, being pregnant, and their level of physical activity. Direct sun rays have a notable impact on perceived temperature, which can raise the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly relevant to babies and toddlers. In general, children are more at risk than adults because they sweat less. Furthermore, the large skin surface compared to their small bodies and the high heat production due to their actions contribute to this vulnerability.
The human body normally cools itself by perspiration. Excessive warmth is eliminated from the body by evaporation of sweat. In high relative humidity, the body's ability to evaporate heat is diminished, resulting in a heightened feeling of warmth. Temperature imbalances caused by excessive heat retention can trigger heat-related maladies.

Humidity

The months with the highest humidity in Ha Long are August and September, with an average relative humidity of 83%.

Rainfall

In Ha Long, during September, the rain falls for 22.9 days and regularly aggregates up to 232mm (9.13") of precipitation. In Ha Long, during the entire year, the rain falls for 237.1 days and collects up to 1472mm (57.95") of precipitation.

Sea temperature

In Ha Long, in September, the average water temperature is 29.3°C (84.7°F).
Note: For swimming, diving, and other water activities, temperatures between 25°C (77°F) and 29°C (84.2°F) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

Daylight

The average length of the day in September in Ha Long is 12h and 16min.
On the first day of September, sunrise is at 05:35 and sunset at 18:08. On the last day of the month, sunrise is at 05:42 and sunset at 17:40 +07.

Sunshine

In September, the average sunshine is 8.1h.

UV index

The average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health vulnerability from exposure to the Sun's UV radiation for average individuals.
Note: In September, a daily maximum UV index of 6 leads to the following instructions:
Implement precautions and maintain sun safety methods. Avoidance of sunburn is demanded. Avoid direct Sun exposure from 10 a.m. to 4 p.m., a period when UV radiation is most intense, and remember that not all shade structures provide full protection. Boost your sun resistance with garments that are densely woven yet spacious. Alert! UV radiation becomes sharper due to reflections from sand and water.