Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The move into September indicates a slight reduction in the average high-temperature, down from August's moderately hot 78.4°F (25.8°C) to a pleasant 69.8°F (21°C). Against the high September temperatures, Sisters records an average drop to a chilly 45.1°F (7.3°C) at night.Humidity
In September, the average relative humidity is 61%.Rainfall
In Sisters, during September, the rain falls for 8.1 days and regularly aggregates up to 1.02" (26mm) of precipitation. In Sisters, during the entire year, the rain falls for 142.1 days and collects up to 22.87" (581mm) of precipitation.Snowfall
January through May, September through December are months with snowfall. September is the first month it typically snows in Sisters. Throughout September, in the average 0.3 snowfall days, it receives 0.87" (22mm) of snow. Throughout the year, in Sisters, there are 70.7 snowfall days, and 60.04" (1525mm) of snow is accumulated.Daylight
The average length of the day in September is 12h and 29min.On the first day of the month, sunrise is at 6:30 am and sunset at 7:41 pm. On the last day of September, sunrise is at 7:03 am and sunset at 6:48 pm PDT.
Sunshine
In September, the average sunshine is 10.6h.UV index
In September, the average daily maximum UV index in Sisters is 3. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV radiation for the average person.Note: An average maximum UV index of 3 in September leads to these recommendations:
Adopt protective measures - It is advised to guard against sun damage. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage. Be attentive! The reflective property of snow can nearly double the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the usual temperature for Sisters in September?
What is the average humidity in September?
How much does it rain in September?
When does it start snowing?
What is the average length of the day in September in Sisters?
What time are sunrise and sunset in September?
How long on average sun shines in September?
How high is the UV index in September?
Average temperature in September
Sisters, OR
- Average high temperature in September: 69.8°F
The warmest month (with the highest average high temperature) is July (78.8°F).
The month with the lowest average high temperature is December (36.5°F).
- Average low temperature in September: 45.1°F
The month with the highest average low temperature is August (50.7°F).
The coldest month (with the lowest average low temperature) is December (24.8°F).
Average pressure in September
Sisters, OR
- Average pressure in September: 30"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is August (29.98"Hg).
Average wind speed in September
Sisters, OR
- Average wind speed in September: 4.8mph
The windiest month (with the highest average wind speed) is February (6.1mph).
The calmest months (with the lowest average wind speed) are August and September (4.8mph).
Average humidity in September
Sisters, OR
- Average humidity in September: 61%
The month with the highest relative humidity is December (84%).
The months with the lowest relative humidity are July and August (53%).
Average rainfall in September
Sisters, OR
- Average rainfall in September: 1.02"
The wettest month (with the highest rainfall) is January (3.31").
The driest month (with the least rainfall) is July (0.35").
Average rainfall days in September
Sisters, OR
- Average rainfall days in September: 8.1 days
The month with the highest number of rainy days is March (16.9 days).
The month with the least rainy days is July (5 days).
Average snowfall in September
Sisters, OR
- Average snowfall in September: 0.87"
The month with the highest snowfall is February (13.74").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Sisters, OR
- Average snowfall days in September: 0.3 days
The month with the highest number of snowfall days is December (14.7 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Sisters, OR
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 30min).
The month with the shortest days is December (Average daylight: 8h and 54min).
- Average sunshine in September: 10h and 4min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 6min).
Average sunshine days in September
Sisters, OR
- Average sunshine days in September: 18.9 days
The month with the most sunshine days is July (23.3 days).
The month with the least sunshine days is March (8.1 days).
Average UV index in September
Sisters, OR
- Average UV index in September: 3
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is February (UV index 1).
Average cloud cover in September
Sisters, OR
- Average cloud cover in September: 21
The months with the most cloud cover are January, February, March and December (Cloud cover 49).
The month with the least cloud cover is July (Cloud cover 11).
Average visibility in September
Sisters, OR
- Average visibility in September: 6mi
The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February, March and December (5mi).
Sisters, Oregon, USA
Weather forecast for your location
2. Allow the app to use your location