September weather forecast
Nagasaki, Japan

September brings the first signs of fall to Nagasaki with a decline in temperature from 31.7°C (89.1°F) to 28.6°C (83.5°F) in the higher range, and from 25.1°C (77.2°F) to 21.8°C (71.2°F) on the low end. A slight decrease in rainfall to 189mm (7.44") signals the definitive end of the monsoon season. As residents bid farewell to the summer, the changing foliage and milder weather bring a beauty all their own. Local festivities embrace the fall season, with the city becoming a palette of vibrant colors. As September gives way to October, temperatures continue to drop, heralding the approach of a cooler season.

Temperature

With the onset of September, Nagasaki's average high-temperature slightly adjusts, moderately receding from August's tropical 31.7°C (89.1°F) to a warm 28.6°C (83.5°F). Throughout September, an average low-temperature of 21.8°C (71.2°F) is experienced.

Heat index

The heat index value for September is appraised at a tropical 32°C (89.6°F). Continuous exposure and activity could induce a sense of tiredness and subsequently, heat cramps.
It is worth noting that heat index values are gauged for conditions in the shade and light breezes. Exposure to the direct sun could elevate the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'real feel', is calculated by taking the relative humidity value for a specific location and factoring it into the air temperature reading. This effect tends to be personal, with the weather perception differing among individuals due to variations in body mass, height, and exertion. One's exposure to direct sunlight has the potential to intensify the heat sensation, increasing the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly critical to babies and toddlers. Children frequently underestimate the necessity to rest and hydrate. Thirst is a late sign of dehydration - thus, it is vital to stay hydrated, particularly during lengthy physical exercises.

Humidity

In September, the average relative humidity in Nagasaki is 73%.

Rainfall

In Nagasaki, Japan, in September, during 9.7 rainfall days, 189mm (7.44") of precipitation is typically accumulated. Throughout the year, in Nagasaki, there are 124.7 rainfall days, and 1858mm (73.15") of precipitation is accumulated.

Snowfall

In Nagasaki, Japan, snow does not fall in March through November.

Sea temperature

In Nagasaki, in September, the average water temperature is 26.7°C (80.1°F).
Note: Swimming, diving, and other water activities in the temperature range of 25°C (77°F) to 29°C (84.2°F) are perceived as very enjoyable and comfortable for prolonged durations.

Daylight

In September, the average length of the day in Nagasaki is 12h and 23min.
On the first day of September, sunrise is at 05:55 and sunset at 18:45. On the last day of the month, sunrise is at 06:14 and sunset at 18:06 JST.

Sunshine

In Nagasaki, the average sunshine in September is 5.8h.

UV index

The average daily maximum UV index in September in Nagasaki is 9. A UV Index of 8 to 10 symbolizes a very high threat to health from unsafe exposure to UV radiation for ordinary individuals.
Note: The maximum daily UV index, 9 in September, converts into the following recommendations:
Immediate precautions are necessary; otherwise, skin and eyes might get damaged quickly. Stay in the shade and limit sun exposure from 10 a.m. to 4 p.m., when UV radiation is most potent. Keep in mind that shade structures like parasols or canopies do not offer full protection. To cut down UV radiation exposure by about half, sport a wide-brim hat. After a swim or an outdoor workout, generously apply and regularly reapply a sunscreen with at least SPF 30, even if the day is cloudy. Be vigilant! The Sun's UV rays get a boost from sand and water reflections.