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 transition into September involves a decrease in the average high-temperature, falling from a moderately hot 84.2°F (29°C) in August to a pleasant 72.7°F (22.6°C). In the month of September, Grand Coulee records a consistent average low-temperature of 53.2°F (11.8°C).Humidity
The average relative humidity in September in Grand Coulee is 45%.Rainfall
In Grand Coulee, in September, during 5.5 rainfall days, 0.43" (11mm) of precipitation is typically accumulated. In Grand Coulee, during the entire year, the rain falls for 102.1 days and collects up to 9.65" (245mm) of precipitation.Snowfall
January through April, September through December are months with snowfall in Grand Coulee. September is the first month it typically snows in Grand Coulee. Throughout September, in the average 0.1 snowfall days, it receives 0.08" (2mm) of snow. In Grand Coulee, Washington, during the entire year, snow falls for 33.4 days and aggregates up to 14.65" (372mm) of snow.Daylight
The average length of the day in September is 12h and 33min.On the first day of the month, sunrise is at 6:15 am and sunset at 7:36 pm. On the last day of September, in Grand Coulee, sunrise is at 6:55 am and sunset at 6:36 pm PDT.
Sunshine
In September, the average sunshine in Grand Coulee is 10.7h.UV index
The average daily maximum UV index in September in Grand Coulee is 4. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for the ordinary person.Note: In September, the average maximum UV index of 4 translates into the following recommendations:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days. Heads up! The UV radiation from the Sun can almost be doubled by snow reflection.
Frequently asked questions
What is the usual temperature for Grand Coulee in September?
What is the average humidity in September in Grand Coulee?
How many days does it rain in September in Grand Coulee?
When does it start snowing in Grand Coulee?
How many hours of daylight does Grand Coulee have in September?
When are sunrise and sunset in September in Grand Coulee?
How many hours of sunshine does Grand Coulee have in September?
What is the UV index reading in September in Grand Coulee?
Average temperature in September
Grand Coulee, WA
- Average high temperature in September: 72.7°F
The warmest month (with the highest average high temperature) is July (84.9°F).
The month with the lowest average high temperature is December (31.6°F).
- Average low temperature in September: 53.2°F
The month with the highest average low temperature is August (61.3°F).
The coldest month (with the lowest average low temperature) is December (21.4°F).
Average pressure in September
Grand Coulee, WA
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.18"Hg).
The month with the lowest atmospheric pressure is August (29.91"Hg).
Average wind speed in September
Grand Coulee, WA
- Average wind speed in September: 5.8mph
The windiest month (with the highest average wind speed) is April (7mph).
The calmest month (with the lowest average wind speed) is January (4.9mph).
Average humidity in September
Grand Coulee, WA
- Average humidity in September: 45%
The month with the highest relative humidity is January (89%).
The month with the lowest relative humidity is August (36%).
Average rainfall in September
Grand Coulee, WA
- Average rainfall in September: 0.43"
The wettest months (with the highest rainfall) are May and December (1.18").
The driest months (with the least rainfall) are July and August (0.2").
Average rainfall days in September
Grand Coulee, WA
- Average rainfall days in September: 5.5 days
The month with the highest number of rainy days is March (12.1 days).
The month with the least rainy days is August (3.2 days).
Average snowfall in September
Grand Coulee, WA
- Average snowfall in September: 0.08"
The month with the highest snowfall is January (4.41").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in September
Grand Coulee, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is December (10.5 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Grand Coulee, 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 30min).
- Average sunshine in September: 10h and 4min
The month with the most sunshine is August (Average sunshine: 12h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).
Average sunshine days in September
Grand Coulee, WA
- Average sunshine days in September: 23.3 days
The month with the most sunshine days is August (25.8 days).
The month with the least sunshine days is March (14.7 days).
Average UV index in September
Grand Coulee, WA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 7).
The month with the lowest UV index is November (UV index 1).
Average cloud cover in September
Grand Coulee, WA
- Average cloud cover in September: 18
The month with the most cloud cover is January (Cloud cover 55).
The months with the least cloud cover are July and August (Cloud cover 12).
Average visibility in September
Grand Coulee, WA
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and December (4mi).
Grand Coulee, Washington, USA
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