Grand Coulee
Washington, USA
Long-term weather forecast
Long-term weather forecast

Monthly weather forecast and climate
Grand Coulee, WA

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Contents

Weather in January

January is a wintry winter month in Grand Coulee, Washington, with temperature in the range of an average low of 21.9°F (-5.6°C) and an average high of 32°F (0°C). In January, the average high-temperature is essentially the same as in December - a cold 32°F (0°C). Weather in January »

Weather in February

The last month of the winter, February, is another cold month in Grand Coulee, Washington, with average temperature fluctuating between 35.6°F (2°C) and 24.1°F (-4.4°C). In February, the average high-temperature is almost the same as in January - a still wintry 35.6°F (2°C). Weather in February »

Weather in March

March, the first month of the spring, in Grand Coulee, is a frosty month, with average temperature varying between 46°F (7.8°C) and 32°F (0°C). In March, the average high-temperature increases, from a wintry 35.6°F (2°C) in February, to a chilly 46°F (7.8°C). Weather in March »

Weather in April

April is a moderate spring month in Grand Coulee, Washington, with average temperature ranging between min 37.9°F (3.3°C) and max 57°F (13.9°C). In Grand Coulee, the average high-temperature increases, from a chilly 46°F (7.8°C) in March, to a mild 57°F (13.9°C). Weather in April »

Weather in May

The last month of the spring, May, is an enjoyable month in Grand Coulee, Washington, with average temperature ranging between max 67.6°F (19.8°C) and min 46°F (7.8°C). In May, the average high-temperature rises, from a moderate 57°F (13.9°C) in April, to an enjoyable 67.6°F (19.8°C). Weather in May »

Weather in June

June, the first month of the summer, in Grand Coulee, is a moderately hot month, with average temperature varying between 74.3°F (23.5°C) and 51.8°F (11°C). In June, the average high-temperature slightly increases, from an enjoyable 67.6°F (19.8°C) in May, to a moderately hot 74.3°F (23.5°C). Weather in June »

Weather in July

July, like June, in Grand Coulee, Washington, is a moderately hot summer month, with temperature in the range of an average high of 84.9°F (29.4°C) and an average low of 59.7°F (15.4°C). July is the warmest month, with an average high-temperature of 84.9°F (29.4°C) and an average low-temperature of 59.7°F (15.4°C). Weather in July »

Weather in August

August, the last month of the summer, in Grand Coulee, is also a moderately hot month, with average temperature fluctuating between 84.2°F (29°C) and 61.3°F (16.3°C). In August, the average high-temperature is essentially the same as in July - a still moderately hot 84.2°F (29°C). Weather in August »

Weather in September

The first month of the autumn, September, is also an agreeable month in Grand Coulee, Washington, with temperature in the range of an average high of 72.7°F (22.6°C) and an average low of 53.2°F (11.8°C). In Grand Coulee, the average high-temperature in September decreases, from a moderately hot 84.2°F (29°C) in August, 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 a moderate autumn month, with temperature in the range of an average high of 56.3°F (13.5°C) and an average low of 41.4°F (5.2°C). In Grand Coulee, the average high-temperature in October plummets, from a pleasant 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 average temperature fluctuating between 41.4°F (5.2°C) and 30.7°F (-0.7°C). In Grand Coulee, the average high-temperature plummets, from a mild 56.3°F (13.5°C) in October, to a wintry 41.4°F (5.2°C). Weather in November »

Weather in December

December, the first month of the winter, in Grand Coulee, is still a freezing cold month, with average temperature varying between 21.4°F (-5.9°C) and 31.6°F (-0.2°C). The coldest month is December, with an average high-temperature of 31.6°F (-0.2°C) and an average low-temperature of 21.4°F (-5.9°C). Weather in December »

FAQ

What is the most humid month in Grand Coulee?

January is the most humid month in Grand Coulee, Washington, with an average relative humidity of 89%.

How many days does it rain in Grand Coulee?

In Grand Coulee, Washington, during the entire year, the rain falls for 102.1 days and collects up to 9.65" (245mm) of precipitation.

When does it snow in Grand Coulee?

Months with snowfall are January through April, September through December.

How many days does it snow in Grand Coulee?

Throughout the year, in Grand Coulee, Washington, there are 33.4 snowfall days, and 14.65" (372mm) of snow is accumulated.

When does it snow the most in Grand Coulee?

The month with the most snowfall in Grand Coulee, Washington, is January when snow falls for 8.4 days and typically aggregates up to 4.41" (112mm) of snow.

What is the month with the least sunshine in Grand Coulee?

January has the least sunshine of the year, with an average of 4.1h of sunshine.

What is the wettest month in Grand Coulee?

Months with the most rainfall are May and December, with an average 1.18" (30mm) of precipitation.

When it does not snow in Grand Coulee?

May through August are months without snowfall.

When are the longest days in Grand Coulee?

June has the longest days of the year in Grand Coulee, Washington, with an average of 16h of daylight.

What is the warmest month in Grand Coulee?

July is the warmest month, with an average high-temperature of 84.9°F (29.4°C) and an average low-temperature of 59.7°F (15.4°C).

What is the driest month in Grand Coulee?

Months with the least rainfall in Grand Coulee, Washington, are July and August Rain falls for 4.2 days and accumulates 0.2" (5mm) of rain.

When is the highest UV index in Grand Coulee?

July is the month with the highest UV index in Grand Coulee, with an average maximum UV index of 7.

What is the least humid month in Grand Coulee?

The least humid month in Grand Coulee, Washington, is August, with an average relative humidity of 36%.

What month has the most sunshine in Grand Coulee?

With an average of 12.1h of sunshine, August has the most sunshine of the year in Grand Coulee, Washington.

What is the month with the lowest UV index in Grand Coulee?

With an average maximum UV index of 1, November is the month with the lowest UV index in Grand Coulee.

What is the coldest month in Grand Coulee?

The coldest month is December, with an average high-temperature of 31.6°F (-0.2°C) and an average low-temperature of 21.4°F (-5.9°C).

What is the month with the shortest days in Grand Coulee?

December has the shortest days of the year, with an average of 8.5h of daylight.

Average temperature
Grand Coulee, WA

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 humidity
Grand Coulee, WA

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 - Grand Coulee, WA

Wettest months (with the highest rainfall) are May and December (1.18").
Driest months (with the lowest rainfall) are July and August (0.2").

Average rainfall days
Grand Coulee, WA

Average rainfall days - Grand Coulee, WA

The month with the highest number of rainy days is March (12.1 days).
The month with the lowest number of rainy days is August (3.2 days).

Average snowfall
Grand Coulee, WA

Average snowfall - Grand Coulee, WA

The month with the highest snowfall is January (4.41").
Months with the lowest snowfall are May, June, July and August (0").

Average snowfall days
Grand Coulee, WA

Average snowfall days - Grand Coulee, WA

The month with the highest number of snowfall days is December (10.5 days).
Months with the lowest number of snowfall days are May, June, July and August (0 days).

Average daylight / Average sunshine
Grand Coulee, WA

Average daylight / Average sunshine - Grand Coulee, WA

The month with the longest days is June (Average daylight: 16h).
The month with shortest days is December (Average daylight: 8.5h).

The month with most sunshine is August (Average sunshine: 12.1h).
The month with least sunshine is January (Average sunshine: 4.1h).

Average UV index
Grand Coulee, WA

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).