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
A subtle decrease in the average high-temperature marks September, falling from August's warm 24.9°C (76.8°F) to a comfortable 18.5°C (65.3°F). Despite considerable daily temperature swings, a steady low-temperature average of 5.6°C (42.1°F) is noted throughout September.Humidity
In September, the average relative humidity in Twisp is 60%.Rainfall
In Twisp, in September, during 9.8 rainfall days, 24mm (0.94") of precipitation is typically accumulated. In Twisp, during the entire year, the rain falls for 141.4 days and collects up to 459mm (18.07") of precipitation.Snowfall
January through April, September through December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 2mm (0.08") of snow. In Twisp, during the entire year, snow falls for 64.4 days and aggregates up to 1082mm (42.6") of snow.Daylight
In September, the average length of the day is 12h and 34min.On the first day of September, sunrise is at 6:19 am and sunset at 7:41 pm. On the last day of the month, sunrise is at 6:59 am and sunset at 6:40 pm PDT.
Sunshine
In Twisp, the average sunshine in September is 10.7h.UV index
In Twisp, the average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a medium health hazard from unprotected exposure to Sun's UV rays for the average person.Note: The maximum UV index of 3 during September leads to these instructions:
Proceed with care. Light skin individuals may be exposed to burns in fewer than 30 minutes. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly. Heed this! Snow reflection can almost augment the UV radiation of the sun by double.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September?
How much does it rain in September?
When does it start to snow?
How many hours of daylight does Twisp have in September?
When 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
Twisp, WA
- Average high temperature in September: 18.5°C
The warmest month (with the highest average high temperature) is August (24.9°C).
The month with the lowest average high temperature is December (-2.3°C).
- Average low temperature in September: 5.6°C
The month with the highest average low temperature is August (9.4°C).
The coldest month (with the lowest average low temperature) is December (-9.6°C).
Average pressure in September
Twisp, WA
- Average pressure in September: 1015.1mbar
The month with the highest atmospheric pressure is January (1021.1mbar).
The month with the lowest atmospheric pressure is August (1014mbar).
Average wind speed in September
Twisp, WA
- Average wind speed in September: 7.5km/h
The windiest month (with the highest average wind speed) is July (8.2km/h).
The calmest months (with the lowest average wind speed) are January and December (5.6km/h).
Average humidity in September
Twisp, WA
- Average humidity in September: 60%
The months with the highest relative humidity are January and February (92%).
The months with the lowest relative humidity are July and August (51%).
Average rainfall in September
Twisp, WA
- Average rainfall in September: 24mm
The wettest month (with the highest rainfall) is December (64mm).
The driest month (with the least rainfall) is July (9mm).
Average rainfall days in September
Twisp, WA
- Average rainfall days in September: 9.8 days
The month with the highest number of rainy days is March (17.1 days).
The month with the least rainy days is August (5.7 days).
Average snowfall in September
Twisp, WA
- Average snowfall in September: 2mm
The month with the highest snowfall is December (312mm).
The months with the least snowfall are May, June, July and August (0mm).
Average snowfall days in September
Twisp, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is December (15.5 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Twisp, WA
- Average daylight in September: 12h and 4min
The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 24min).
- Average sunshine in September: 10h and 4min
The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in September
Twisp, WA
- Average sunshine days in September: 17.6 days
The month with the most sunshine days is August (22.8 days).
The month with the least sunshine days is March (8.9 days).
Average UV index in September
Twisp, WA
- Average UV index in September: 3
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February and November (UV index 1).
Average cloud cover in September
Twisp, WA
- Average cloud cover in September: 22
The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is August (Cloud cover 14).
Average visibility in September
Twisp, WA
- Average visibility in September: 10km
The months with the highest visibility are June, July, August and September (10km).
The month with the lowest visibility is January (5km).
Twisp, Washington, USA
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