September weather forecast
Hanoi, Vietnam

The weather in September brings about somewhat cooler temperatures compared to the previous summer months. Significantly, compared to August, precipitation decreases considerably to 73mm (2.87"). This dip in rainfall coupled with lower temperatures signifies the commencement of autumn. This cool and comfortably moist setting of September gradually progresses into October, bringing with it slightly cooler temperatures and reducing the volume of rain.

Temperature

Hanoi, Vietnam, notes an average high-temperature of a still hot 31.7°C (89.1°F) in September, hardly diverging from August. During September, the temperature tends to dip to an average of 24.2°C (75.6°F) at night.

Heat index

For most parts of September, the heat index is evaluated at an extremely hot 43°C (109.4°F). Stay mindful: Heat exhaustion and heat cramps are likely. Heatstroke could follow extended physical effort.
Understand that the heat index values take into account shaded locations and mild winds. The heat index may scale up by 15 Fahrenheit (8 Celsius) degrees with direct sun exposure.
Note: The heat index, also known as 'apparent temperature' or 'feels like', gauges the sensation of temperature factoring in the air's moisture content. Elements such as metabolic variations, being pregnant, and physical activity can impact one's weather perception. Should you be directly under the sun, anticipate a possible increase in the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly important for children. Kids frequently fail to realize the necessity for resting and hydrating. Thirst is an advanced indication of dehydration - hence, maintaining hydration, especially during extended physical activities, becomes essential.
The physiological way the human body responds to excessive heat is by inducing perspiration, using sweat evaporation as a cooling mechanism. Elevated relative humidity disrupts typical body cooling by reducing the evaporation rate, consequently decreasing the body's cooling rate and enhancing the feeling of heat. Excessive heat gain, when not shed effectively by the body, can result in increasing body temperatures and related hazards.

Humidity

August and September, with an average relative humidity of 80%, are the most humid months in Hanoi.

Rainfall

In Hanoi, Vietnam, in September, during 18.5 rainfall days, 73mm (2.87") of precipitation is typically accumulated. Throughout the year, in Hanoi, there are 181.2 rainfall days, and 595mm (23.43") of precipitation is accumulated.

Daylight

In September, the average length of the day is 12h and 16min.
On the first day of September, sunrise is at 05:40 and sunset at 18:12. On the last day of the month, sunrise is at 05:47 and sunset at 17:45 +07.

Sunshine

The average sunshine in September is 8.5h.

UV index

May through September, with an average maximum UV index of 7, are months with the highest UV index. A UV Index estimate of 6 to 7 represents a high health vulnerability from exposure to the Sun's UV rays for the average person.
Note: In September, an average UV index of 7 transforms into the following instructions:
Inhibit overexposure. Warding off sun damage is of utmost importance. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a period when UV radiation is particularly strong, noting that parasols or canopies may not offer total sun protection. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense.