September weather forecast
Vientiane, Laos

September witnesses a reduction in the rainfall from 335mm (13.19") in August to a more manageable 297mm (11.69") in Vientiane, Laos. This drop in rainfall comes with a slight decrease in temperatures and relative humidity. The weather signals the impending arrival of the cooler months, which citizens anticipate eagerly. The change in weather also ushers in the season of harvest, a significant and joyous occasion in Laos.

Temperature

As August turns into September, the average high-temperatures rest at a still tropical 30.9°C (87.6°F), showing a minor variation from the prior month. The average low-temperature of 24.1°C (75.4°F) is witnessed during September.

Heat index

September's heat index is estimated at a blisteringly hot 42°C (107.6°F). More protective measures are required - heat exhaustion and heat cramps are likely. Heatstroke may follow lengthy activity.
Be aware that heat index ratings are designed for shaded locations and minor breezes. The heat index might be elevated by 15 Fahrenheit (8 Celsius) degrees due to direct sun exposure.
Note: The heat index, also known as 'real feel' or 'felt air temperature', embodies the combination of air temperature and moisture content to illustrate perceived heat. The impact of weather is personal, differing among a variety of people based on differences in body mass, height, and the level of physical exertion. 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 primarily vital for children. Children regularly disregard the necessity to rest and replenish fluids. Thirst is a late symptom of dehydration - thus, maintaining hydration, particularly during long-lasting physical activities, is essential.
The human body cools itself through perspiration, as excessive warmth is removed from the body through sweat evaporation. Heightened relative humidity interferes with the body's usual cooling mechanism by reducing evaporation, subsequently decreasing the body's cooling rate and increasing the sensation of heat. Overheating risks increase with rising body temperatures, especially if heat release isn't efficient.

Humidity

In September, the average relative humidity is 83%.

Rainfall

In September, the rain falls for 17 days. Throughout September, 297mm (11.69") of precipitation is accumulated. In Vientiane, during the entire year, the rain falls for 118 days and collects up to 1661mm (65.39") of precipitation.

Daylight

In Vientiane, the average length of the day in September is 12h and 14min.
On the first day of September, sunrise is at 05:55 and sunset at 18:23. On the last day of the month, sunrise is at 05:59 and sunset at 17:59 +07.

Sunshine

The average sunshine in September in Vientiane is 4.6h.

UV index

The months with the highest UV index are March through September, with an average maximum UV index of 12. A UV Index estimate of 11, and higher, represents an excessive health risk from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: The UV index of 12 during September leads to these advisories:
Carry out all vital precautions. Protection from sun exposure is a must. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Broad-spectrum SPF 30+ sunscreen must be generously applied and reapplied every two hours or post any outdoor activity or swim.