Climate and monthly weather forecastGrand Coulee, WA
Climate and monthly weather forecast
Weather in January
January is a wintry winter month in Grand Coulee, Washington, with an average temperature fluctuating between 32°F (0°C) and 21.9°F (-5.6°C). Grand Coulee's transition from December to January introduces an average high-temperature of an icy 32°F (0°C), marking an insignificant variation from the 31.6°F (-0.2°C). Weather in January »Weather in February
The last month of the winter, February, is another cold month in Grand Coulee, Washington, with an average temperature ranging between max 35.6°F (2°C) and min 24.1°F (-4.4°C). The arrival of February sees a recorded average high-temperature of a still wintry 35.6°F (2°C), showing little divergence from the previous month's conditions. Weather in February »Weather in March
March, the first month of the spring in Grand Coulee, is a chilly month, with an average temperature varying between 32°F (0°C) and 46°F (7.8°C). The transition to March introduces an increase in the average high-temperature, shifting from an icy 35.6°F (2°C) in February to a frosty 46°F (7.8°C). Weather in March »Weather in April
April in Grand Coulee, Washington, is a mild spring month, with an average temperature fluctuating between 57°F (13.9°C) and 37.9°F (3.3°C). Entering April, Grand Coulee sees a temperature rise, with the average high-temperature advancing from March's chilly 46°F (7.8°C) to a refreshing 57°F (13.9°C). Weather in April »Weather in May
The last month of the spring, May, is a comfortable month in Grand Coulee, Washington, with an average temperature fluctuating between 46°F (7.8°C) and 67.6°F (19.8°C). The shift from April to May sees an increase in the average high-temperature, transitioning from a refreshing 57°F (13.9°C) to a comfortable 67.6°F (19.8°C). Weather in May »Weather in June
The first month of the summer, June, is a moderately hot month in Grand Coulee, Washington, with an average temperature ranging between max 74.3°F (23.5°C) and min 51.8°F (11°C). As June arrives, Grand Coulee's weather shows a minor increase in high-temperatures, edging from May's enjoyable 67.6°F (19.8°C) to a moderately hot 74.3°F (23.5°C). Weather in June »Weather in July
July, the same as June, is a moderately hot summer month in Grand Coulee, Washington, with an average temperature fluctuating between 84.9°F (29.4°C) and 59.7°F (15.4°C). With average high temperatures of 84.9°F (29.4°C) and lows of 59.7°F (15.4°C), July is the warmest month. Weather in July »Weather in August
The last month of the summer, August, is also a moderately hot month in Grand Coulee, Washington, with an average temperature ranging between max 84.2°F (29°C) and min 61.3°F (16.3°C). Grand Coulee marks the onset of August with an average high-temperature of a still warm 84.2°F (29°C), subtly divergent from July's 84.9°F (29.4°C). Weather in August »Weather in September
The first month of the autumn, September, is still a pleasant month in Grand Coulee, Washington, with an average temperature ranging between max 72.7°F (22.6°C) and min 53.2°F (11.8°C). Grand Coulee's September weather shows a moderate shift in high-temperatures, falling from August's moderately hot 84.2°F (29°C) to an agreeable 72.7°F (22.6°C). Weather in September »Weather in October
October, the same as September, in Grand Coulee, Washington, is another mild autumn month, with an average temperature fluctuating between 41.4°F (5.2°C) and 56.3°F (13.5°C). October is marked by a significant decrease, with the average high-temperature retreating from an agreeable 72.7°F (22.6°C) in September to a mild 56.3°F (13.5°C). Weather in October »Weather in November
The last month of the autumn, November, is another cold month in Grand Coulee, Washington, with an average temperature fluctuating between 41.4°F (5.2°C) and 30.7°F (-0.7°C). A notable decrease in the average high-temperature is observed during November, falling from a moderate 56.3°F (13.5°C) in October to a wintry 41.4°F (5.2°C). Weather in November »Weather in December
The first month of the winter, December, is also a subzero cold month in Grand Coulee, Washington, with an average temperature fluctuating between 31.6°F (-0.2°C) and 21.4°F (-5.9°C). Grand Coulee experiences its lowest average temperatures in December, reaching a peak of 31.6°F (-0.2°C) and a minimum of 21.4°F (-5.9°C). Weather in December »Updated: Jul 28, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
January is the most humid month, with an average relative humidity of 89%.
Throughout the year, there are 102.1 rainfall days, and 9.65" (245mm) of precipitation is accumulated.
Months with snowfall are January through April, September through December.
January is the month with the most snowfall. Snow falls for 8.4 days and accumulates 4.41" (112mm) of snow.
Throughout the year, in Grand Coulee, there are 33.4 snowfall days, and 14.65" (372mm) of snow is accumulated.
January has the least sunshine of the year, with an average of 4.1h of sunshine.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from PST to PDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from PDT to PST.
The months with the most rainfall are May and December, with an average 1.18" (30mm) of precipitation.
In Grand Coulee, snow does not fall in May through August.
With an average of 16h and 0min of daylight, June has the longest days of the year.
The highest temperatures are recorded in July, with averages reaching a high of 84.9°F (29.4°C) and a low of 59.7°F (15.4°C).
The months with the least rainfall are July and August Rain falls for 4.2 days and accumulates 0.2" (5mm) of rain.
The month with the highest UV index is July, with an average maximum UV index of 7.
The least humid month is August, with an average relative humidity of 36%.
The month with the most sunshine is August, with an average of 12.1h of sunshine.
November is the month with the lowest UV index, with an average maximum UV index of 1.
Grand Coulee's coldest month, December, generally records average temperatures ranging from a high of 31.6°F (-0.2°C) to a low of 21.4°F (-5.9°C).
December has the shortest days of the year, with an average of 8h and 30min of daylight.
Average temperature
Grand Coulee, WA
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).
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
Grand Coulee, WA
- Average pressure in January:
30.18"Hg - Average pressure in February:
30.1"Hg - Average pressure in March:
30.01"Hg - Average pressure in April:
29.98"Hg - Average pressure in May:
29.94"Hg - Average pressure in June:
29.92"Hg
- Average pressure in July:
29.93"Hg - Average pressure in August:
29.91"Hg - Average pressure in September:
29.96"Hg - Average pressure in October:
30.03"Hg - Average pressure in November:
30.08"Hg - Average pressure in December:
30.15"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
Grand Coulee, WA
- Average wind speed in January:
4.9mph - Average wind speed in February:
5.3mph - Average wind speed in March:
6.3mph - Average wind speed in April:
7mph - Average wind speed in May:
6.3mph - Average wind speed in June:
6.3mph
- Average wind speed in July:
6mph - Average wind speed in August:
5.7mph - Average wind speed in September:
5.8mph - Average wind speed in October:
5.9mph - Average wind speed in November:
5.8mph - Average wind speed in December:
5mph
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
Grand Coulee, WA
The month with the highest relative humidity is January (89%).
The month with the lowest relative humidity is August (36%).
Average rainfall
Grand Coulee, WA
- Average rainfall in January:
1.14" - Average rainfall in February:
0.75" - Average rainfall in March:
1.06" - Average rainfall in April:
0.79" - Average rainfall in May:
1.18" - Average rainfall in June:
0.75"
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
Grand Coulee, WA
- Average rainfall days in January:
9.7 days - Average rainfall days in February:
7.8 days - Average rainfall days in March:
12.1 days - Average rainfall days in April:
11.1 days - Average rainfall days in May:
10.8 days - Average rainfall days in June:
8.4 days
- Average rainfall days in July:
4.2 days - Average rainfall days in August:
3.2 days - Average rainfall days in September:
5.5 days - Average rainfall days in October:
10.3 days - Average rainfall days in November:
10.5 days - Average rainfall days in December:
8.5 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
Grand Coulee, WA
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
Grand Coulee, WA
- Average snowfall days in January:
8.4 days - Average snowfall days in February:
6.9 days - Average snowfall days in March:
3.2 days - Average snowfall days in April:
0.8 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0.1 days - Average snowfall days in October:
0.2 days - Average snowfall days in November:
3.3 days - Average snowfall days in December:
10.5 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 / Average sunshine
Grand Coulee, WA
- Average daylight in January:
8h and 54min - Average daylight in February:
10h and 18min - Average daylight in March:
11h and 54min - Average daylight in April:
13h and 42min - Average daylight in May:
15h and 12min - Average daylight in June:
16h and 0min
- Average daylight in July:
15h and 36min - Average daylight in August:
14h and 12min - Average daylight in September:
12h and 36min - Average daylight in October:
10h and 48min - Average daylight in November:
9h and 18min - Average daylight in December:
8h and 30min
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 January:
4h and 6min - Average sunshine in February:
4h and 48min - Average sunshine in March:
7h and 18min - Average sunshine in April:
10h and 6min - Average sunshine in May:
10h and 54min - Average sunshine in June:
11h and 18min
- Average sunshine in July:
11h and 54min - Average sunshine in August:
12h and 6min - Average sunshine in September:
10h and 42min - Average sunshine in October:
6h and 42min - Average sunshine in November:
5h and 30min - Average sunshine in December:
4h and 24min
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
Grand Coulee, WA
- Average sunshine days in January:
16 days - Average sunshine days in February:
14.8 days - Average sunshine days in March:
14.7 days - Average sunshine days in April:
15.8 days - Average sunshine days in May:
18 days - Average sunshine days in June:
19.9 days
- Average sunshine days in July:
25.5 days - Average sunshine days in August:
25.8 days - Average sunshine days in September:
23.3 days - Average sunshine days in October:
19.2 days - Average sunshine days in November:
15.4 days - Average sunshine days in December:
16 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
Grand Coulee, WA
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
Grand Coulee, WA
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
Grand Coulee, WA
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).
