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
Sisters's September weather shows a modest shift in high-temperatures, falling from August's moderately hot 78.4°F (25.8°C) to an agreeable 69.8°F (21°C). Sisters experiences a consistent, yet significant, drop from daily highs to a low-temperature of 45.1°F (7.3°C) throughout September.Humidity
In Sisters, the average relative humidity in September is 61%.Rainfall
In Sisters, in September, it is raining for 8.1 days, with typically 1.02" (26mm) of accumulated precipitation. Throughout the year, in Sisters, there are 142.1 rainfall days, and 22.87" (581mm) of precipitation is accumulated.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. In Sisters, during the entire year, snow falls for 70.7 days and aggregates up to 60.04" (1525mm) of snow.Daylight
In September, the average length of the day is 12h and 29min.On the first day of September, sunrise is at 6:30 am and sunset at 7:41 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:48 pm PDT.
Sunshine
In Sisters, Oregon, the average sunshine in September is 10.6h.UV index
In September, the average daily maximum UV index is 3. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for ordinary individuals.Note: The maximum daily UV index of 3 in September converts into the following recommendations:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. The Sun is most powerful around mid-day, so it's a good practice to reduce direct exposure. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. Remember! The Sun's UV radiation can be magnified almost twofold by the reflection of snow.
Frequently asked questions
What are September temperatures in Sisters?
What is the average humidity in September in Sisters?
How many days does it rain in September in Sisters?
When does it start to snow in Sisters?
What is the average length of the day in September in Sisters?
When are sunrise and sunset in September in Sisters?
How long on average sun shines in September in Sisters?
How high is the UV index in September in Sisters?
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
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