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 arrival of September signals a subtle shift in temperature, down from a moderately hot 77.4°F (25.2°C) in August to an agreeable 70.2°F (21.2°C). Throughout the month of September, Grand Mound observes a dramatic downturn from the daytime peak temperatures, expecting an average low of 47.3°F (8.5°C).Humidity
The average relative humidity in September is 79%.Rainfall
In September, the rain falls for 10.6 days. Throughout September, 1.14" (29mm) of precipitation is accumulated. In Grand Mound, during the entire year, the rain falls for 168 days and collects up to 23.94" (608mm) of precipitation.Snowfall
April through October are months without snowfall.Daylight
In September, the average length of the day is 12h and 32min.On the first day of the month, sunrise is at 6:32 am and sunset at 7:50 pm. On the last day of September, sunrise is at 7:10 am and sunset at 6:52 pm PDT.
Sunshine
The average sunshine in September is 8.3h.UV index
The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for ordinary individuals.Note: A daily maximum UV index of 4 in September translates into the following instructions:
Adopt protective measures - It is advised to guard against sun damage. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection.
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 Grand Mound have in September?
When is the sunrise / sunset in September?
How long on average sun shines in September in Grand Mound?
How high is the UV index in September in Grand Mound?
Average temperature in September
Grand Mound, WA
- Average high temperature in September: 70.2°F
The warmest month (with the highest average high temperature) is August (77.4°F).
The month with the lowest average high temperature is December (42.6°F).
- Average low temperature in September: 47.3°F
The month with the highest average low temperature is August (49.8°F).
The coldest month (with the lowest average low temperature) is December (33.1°F).
Average pressure in September
Grand Mound, WA
- Average pressure in September: 30.02"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The months with the lowest atmospheric pressure are March, August and September (30.02"Hg).
Average wind speed in September
Grand Mound, WA
- Average wind speed in September: 3.6mph
The windiest months (with the highest average wind speed) are January, March and November (4.5mph).
The calmest month (with the lowest average wind speed) is September (3.6mph).
Average humidity in September
Grand Mound, WA
- Average humidity in September: 79%
The month with the highest relative humidity is November (90%).
The month with the lowest relative humidity is July (73%).
Average rainfall in September
Grand Mound, WA
- Average rainfall in September: 1.14"
The wettest month (with the highest rainfall) is January (3.86").
The driest month (with the least rainfall) is July (0.35").
Average rainfall days in September
Grand Mound, WA
- Average rainfall days in September: 10.6 days
The month with the highest number of rainy days is March (19.8 days).
The month with the least rainy days is August (5.6 days).
Average snowfall in September
Grand Mound, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.54").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in September
Grand Mound, WA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2.7 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
Grand Mound, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).
- Average sunshine in September: 8h and 2min
The month with the most sunshine is August (Average sunshine: 10h and 6min).
The month with the least sunshine is December (Average sunshine: 3h and 30min).
Average sunshine days in September
Grand Mound, WA
- Average sunshine days in September: 16.9 days
The month with the most sunshine days is August (20.9 days).
The months with the least sunshine days are February and March (9.3 days).
Average UV index in September
Grand Mound, WA
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Grand Mound, WA
- Average cloud cover in September: 47
The month with the most cloud cover is January (Cloud cover 66).
The months with the least cloud cover are July and August (Cloud cover 38).
Average visibility in September
Grand Mound, WA
- Average visibility in September: 4mi
The month with the highest visibility is July (5mi).
The months with the lowest visibility are January, February, March, April, May, June, August, September, October, November and December (4mi).
Grand Mound, Washington, USA
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