September weather forecastKoyasu, Japan
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Koyasu, Japan, with an average temperature ranging between min 22.3°C (72.1°F) and max 26.1°C (79°F).Temperature
The average high-temperature during September is a still warm 26.1°C (79°F), almost matching the conditions of the preceding month. Koyasu sustains a near constant temperature throughout September, with nighttime averages of 22.3°C (72.1°F).Humidity
The average relative humidity in September in Koyasu is 77%.Rainfall
September is the month with the most rainfall in Koyasu. Rain falls for 16 days and accumulates 125mm (4.92") of precipitation.Snowfall
April through December are months without snowfall.Daylight
In Koyasu, Japan, the average length of the day in September is 12h and 25min.On the first day of September, sunrise is at 05:15 and sunset at 18:10. On the last day of the month, sunrise is at 05:37 and sunset at 17:28 JST.
Sunshine
The average sunshine in September in Koyasu is 8h.UV index
In Koyasu, Japan, the average daily maximum UV index in September is 6. A UV Index value of 6 to 7 symbolizes a high threat to health from exposure to the Sun's UV rays for ordinary 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. The Sun's UV radiation is at its strongest between the hours of 10 a.m. and 4 p.m. Minimize direct exposure to the sun during this period. To cut down UV radiation exposure by about half, sport a wide-brim hat.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Koyasu, Japan
- Average high temperature in September: 26.1°C
The warmest month (with the highest average high temperature) is August (28.8°C).
The month with the lowest average high temperature is January (9.8°C).
- Average low temperature in September: 22.3°C
The month with the highest average low temperature is August (25.3°C).
The coldest month (with the lowest average low temperature) is January (5.3°C).
Average pressure in September
Koyasu, Japan
- Average pressure in September: 1013.2mbar
The month with the highest atmospheric pressure is November (1017.9mbar).
The month with the lowest atmospheric pressure is June (1009.1mbar).
Average wind speed in September
Koyasu, Japan
- Average wind speed in September: 17.3km/h
The windiest month (with the highest average wind speed) is March (20.8km/h).
The calmest month (with the lowest average wind speed) is June (15.9km/h).
Average humidity in September
Koyasu, Japan
- Average humidity in September: 77%
The month with the highest relative humidity is July (83%).
The month with the lowest relative humidity is January (61%).
Average rainfall in September
Koyasu, Japan
- Average rainfall in September: 125mm
The wettest month (with the highest rainfall) is September (125mm).
The driest months (with the least rainfall) are February and December (39mm).
Average rainfall days in September
Koyasu, Japan
- Average rainfall days in September: 16 days
The month with the highest number of rainy days is June (16.5 days).
The month with the least rainy days is January (6.5 days).
Average snowfall in September
Koyasu, Japan
- Average snowfall in September: 0mm
The month with the highest snowfall is February (10mm).
The months with the least snowfall are April, May, June, July, August, September, October, November and December (0mm).
Average snowfall days in September
Koyasu, Japan
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (0.5 days).
The months with the least snowfall days are April, May, June, July, August, September, October, November and December (0 days).
Average daylight in September /
Average sunshine in September
Koyasu, Japan
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 30min).
The month with the shortest days is December (Average daylight: 9h and 48min).
- Average sunshine in September: 8h and 0min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The month with the least sunshine is February (Average sunshine: 5h and 30min).
Average sunshine days in September
Koyasu, Japan
- Average sunshine days in September: 11.2 days
The month with the most sunshine days is January (23.2 days).
The month with the least sunshine days is September (11.2 days).
Average UV index in September
Koyasu, Japan
- Average UV index in September: 6
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February and December (UV index 3).
Average cloud cover in September
Koyasu, Japan
- Average cloud cover in September: 38
The months with the most cloud cover are March, June and October (Cloud cover 43).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility in September
Koyasu, Japan
- Average visibility in September: 10km
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (10km).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (10km).





