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 average high-temperature decreases in September, shifting from a hot 86.2°F (30.1°C) in August to a warm 75.4°F (24.1°C). Nighttime temperature lowers to an average of 54.9°F (12.7°C) in September.Humidity
The average relative humidity in September in Sunnyside is 46%.Rainfall
In Sunnyside, in September, it is raining for 5.5 days, with typically 0.35" (9mm) of accumulated precipitation. In Sunnyside, during the entire year, the rain falls for 104.5 days and collects up to 8.23" (209mm) of precipitation.Snowfall
Months with snowfall are January through March, September, November and December. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.2" (5mm) of snow. In Sunnyside, during the entire year, snow falls for 15.6 days and aggregates up to 7.36" (187mm) of snow.Daylight
The average length of the day in September is 12h and 32min.On the first day of September, sunrise is at 6:21 am and sunset at 7:38 pm. On the last day of the month, sunrise is at 6:58 am and sunset at 6:41 pm PDT.
Sunshine
The average sunshine in September is 10.7h.UV index
In September, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for ordinary individuals.Note: The maximum UV index of 4 during September translates into these guidelines:
Take necessary precautions - Protection from skin and eye injury is mandatory. Sun's radiation is most powerful around mid-day, so it's best to limit outdoor activities during this time. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes. Be aware! The reflective nature of snow can magnify the Sun's UV radiation almost twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the temperature in September?
What is the average humidity in September?
How many days does it rain in September?
When does it start snowing?
What is the average length of the day in September in Sunnyside?
When are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
Sunnyside, WA
- Average high temperature in September: 75.4°F
The warmest month (with the highest average high temperature) is July (87.1°F).
The month with the lowest average high temperature is December (36.1°F).
- Average low temperature in September: 54.9°F
The month with the highest average low temperature is August (61.5°F).
The coldest month (with the lowest average low temperature) is December (25.3°F).
Average pressure in September
Sunnyside, WA
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.17"Hg).
The month with the lowest atmospheric pressure is August (29.92"Hg).
Average wind speed in September
Sunnyside, WA
- Average wind speed in September: 6.6mph
The windiest month (with the highest average wind speed) is April (8.3mph).
The calmest month (with the lowest average wind speed) is December (5mph).
Average humidity in September
Sunnyside, WA
- Average humidity in September: 46%
The month with the highest relative humidity is January (83%).
The months with the lowest relative humidity are July and August (38%).
Average rainfall in September
Sunnyside, WA
- Average rainfall in September: 0.35"
The wettest month (with the highest rainfall) is May (1.1").
The driest month (with the least rainfall) is July (0.24").
Average rainfall days in September
Sunnyside, WA
- Average rainfall days in September: 5.5 days
The month with the highest number of rainy days is March (13.3 days).
The month with the least rainy days is July (4.1 days).
Average snowfall in September
Sunnyside, WA
- Average snowfall in September: 0.2"
The month with the highest snowfall is December (2.24").
The months with the least snowfall are April, May, June, July, August and October (0").
Average snowfall days in September
Sunnyside, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is December (5 days).
The months with the least snowfall days are April, May, June, July, August and October (0 days).
Average daylight in September /
Average sunshine in September
Sunnyside, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- Average sunshine in September: 10h and 4min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 4h and 54min).
Average sunshine days in September
Sunnyside, WA
- Average sunshine days in September: 22.6 days
The month with the most sunshine days is July (26.2 days).
The month with the least sunshine days is March (15.4 days).
Average UV index in September
Sunnyside, WA
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Sunnyside, WA
- Average cloud cover in September: 17
The month with the most cloud cover is January (Cloud cover 50).
The month with the least cloud cover is July (Cloud cover 10).
Average visibility in September
Sunnyside, WA
- Average visibility in September: 6mi
The months with the highest visibility are February, March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and December (5mi).
Sunnyside, Washington, USA
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