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
Sumner's weather subtly changes with the onset of September, barely falling from a warm 75.7°F (24.3°C) in August to an agreeable 68.9°F (20.5°C). In Sumner, the nighttime temperature averages to a chilly 47.7°F (8.7°C) during September.Humidity
In Sumner, the average relative humidity in September is 75%.Rainfall
In Sumner, during September, the rain falls for 12.2 days and regularly aggregates up to 1.61" (41mm) of precipitation. Throughout the year, there are 185 rainfall days, and 35.71" (907mm) of precipitation is accumulated.Snowfall
In Sumner, snow does not fall in May through October.Daylight
The average length of the day in September is 12h and 32min.On the first day of the month, sunrise is at 6:29 am and sunset at 7:48 pm. On the last day of September, sunrise is at 7:07 am and sunset at 6:49 pm PDT.
Sunshine
In September, the average sunshine in Sumner is 9.3h.UV index
The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for ordinary individuals.Note: The maximum UV index of 4 during September translates into these guidelines:
Be mindful. Those with pale skin might receive burns in fewer than 30 minutes. The Sun is most powerful around mid-day, so it's a good practice to reduce direct exposure. Your best bet for sun defense on the face, eyes, and neck is a hat with a wide brim.
Published by: Weather U.S. | About Us
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 it does not snow?
How many hours of daylight does Sumner have in September?
When are sunrise and sunset in September?
How many hours of sunshine does Sumner have in September?
What is the UV index intensity in September?
Average temperature in September
Sumner, WA
- Average high temperature in September: 68.9°F
The warmest month (with the highest average high temperature) is August (75.7°F).
The month with the lowest average high temperature is December (41.4°F).
- Average low temperature in September: 47.7°F
The month with the highest average low temperature is August (50.9°F).
The coldest month (with the lowest average low temperature) is December (32°F).
Average pressure in September
Sumner, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).
Average wind speed in September
Sumner, WA
- Average wind speed in September: 3.7mph
The windiest month (with the highest average wind speed) is January (4.9mph).
The calmest month (with the lowest average wind speed) is August (3.5mph).
Average humidity in September
Sumner, WA
- Average humidity in September: 75%
The month with the highest relative humidity is January (87%).
The months with the lowest relative humidity are July and August (70%).
Average rainfall in September
Sumner, WA
- Average rainfall in September: 1.61"
The wettest month (with the highest rainfall) is December (5.35").
The driest month (with the least rainfall) is July (0.51").
Average rainfall days in September
Sumner, WA
- Average rainfall days in September: 12.2 days
The month with the highest number of rainy days is March (20.7 days).
The month with the least rainy days is August (6.8 days).
Average snowfall in September
Sumner, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (3.31").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Sumner, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (5.3 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Sumner, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 36min).
- Average sunshine in September: 9h and 2min
The month with the most sunshine is August (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 4h and 12min).
Average sunshine days in September
Sumner, WA
- Average sunshine days in September: 16.9 days
The month with the most sunshine days is August (22 days).
The month with the least sunshine days is February (8.2 days).
Average UV index in September
Sumner, WA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February, October, November and December (UV index 2).
Average cloud cover in September
Sumner, WA
- Average cloud cover in September: 35
The months with the most cloud cover are January and December (Cloud cover 56).
The month with the least cloud cover is August (Cloud cover 25).
Average visibility in September
Sumner, WA
- Average visibility in September: 5mi
The months with the highest visibility are July and August (6mi).
The months with the lowest visibility are January, February and December (4mi).
Sumner, Washington, USA
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