Seattle
Washington, USA
Long-term weather forecast
Long-term weather forecast

Monthly weather forecast and climate
Seattle, WA

Beautiful dusk skyline over the giant skyscrapers of Seattle, Washington
Beautiful dusk skyline over the giant skyscrapers of Seattle, Washington
Seattle, the largest city in the Washington State, has a warm, temperate oceanic climate (Köppen climatic classification Cfb) characterized by cool, wet winters and mild, relatively dry summers. The city is located in the lowland area of Puget Sounds between the Olympic Mountains and the Cascade Mountains and is the cloudiest region in the United States. The climate of Seattle is influenced by the dry winds from the slopes of the Cascade Mountains and the Fraser Valley.

Summertime is mildly warm and moderately dry with pleasant temperatures ranging between 68°F (20°C) and 73.4°F (23°C) and a tolerable average humidity of 66.1%. The lovely blue skies, minimal rainfall, and extended daylight hours up to sixteen hours increase the enjoyment of summer.

Winters in Seattle are cold and wet. Rainfall is experienced for an average of eighteen days per month, and the rain gauge collects approximately 5.8" (147.3mm). Snow is not uncommon, accumulating up to 1.7" (43.2mm), mostly in December and February. Humidity averages 79% across the season, and the average sunshine hours per day are two.

Spring and autumn have mildly cold temperatures and moderately rainy days. The skies remain somewhat cloudy, and most days are pleasantly warm and sunny.
The best time to visit Seattle is during the summer, from mid-May to September. The temperatures are warm and pleasant with lows of 53.6°F (12°C) and highs of 73.4°F (23°C).
The sea temperatures are favorable at 57.2°F (14°C). Summers are devoid of the excess winter rainfall and have elongated days making it the best time to tour Seattle. Humidity is tolerable hence the stays are lovely and less sticky.
The Seattle International Film Festival should be a must-go with occasional street displays of popular films. The hotels may be costly, but early booking and reservation guarantee the best prices.

Winter is not the best time to visit Seattle. With extremely low temperatures between 35.6°F (2°C) and 50°F (10°C), outdoor might be almost impossible even for the strong-willed. Most activities are redirected to indoors owing to the chilly winds blowing all the time. Winter experiences the highest rainfall, so most days are bound to be wet and slippery. Snow falls are high and regular accumulating up to 1.7" (43.2mm), and apart from skiing and snow skating, winter has limited activities to enjoy in Seattle.

Owing to its geographical location in the Puget Sound area, Seattle remains susceptible to windstorms and ice storms, which may result in felled trees, which in turn result in great property damage, especially the power lines.
Seattle is lowly placed, and as such, the high rainfall in winter poses a possible flood threat primarily in the lower parts of the city.

January is the coldest month with 78% humidity and extremely low temperatures in the range of 35.6°F (2°C) to 44.6°F (7°C) accompanied by one and a half days of snowing and a resultant 1.4" (35.6mm) of snowfall. Weather in January »

February is still a cold month, and it comes with a decrease in humidity to 75% and an increase in the temperatures to the range of 37.4°F (3°C) and 50°F (10°C). Snowfall reduces to only one day on average. Weather in February »

March is the start of spring in Seattle. It is characterized by a further drop in humidity to 73.1% and a significant rise in temperatures to the range of 37.4°F (3°C) and 53.6°F (12°C) making the weather warmer and more pleasant, especially with the five daily hours of sunshine. Weather in March »

The temperatures are mildly warmer and more pleasant in the range of 41°F (5°C) and 57.2°F (14°C), and there is a further drop in relative humidity to 70.8%. Weather in April »

May is the loveliest month in Seattle as the days begin to become longer than nights. Temperatures rise to a moderately warm range of 46.4°F (8°C) to 64.4°F (18°C). Weather in May »

Summer begins officially in June bringing with it a tolerable 66.8% humidity and warmer temperatures in the range of 51.8°F (11°C) and 69.8°F (21°C). Weather in June »

Temperatures are the most pleasant in the range of 55.4°F (13°C), and 73.4°F (23°C) and touring Seattle becomes most comfortable, especially with sixteen hours of daylight. Weather in July »

August remains moderately warm and pleasant with the temperatures in the range of 55.4°F (13°C) and 73.4°F (23°C), but witnesses significant rise in humidity to 68%. Weather in August »

September is transitional month and experiences summer weather only for the first few weeks. With a significant rise in humidity to 72.9%, temperatures in September cool to the range of 51.8°F (11°C) and 68°F (20°C) as autumn arrives. Weather in September »

Mildly warm and pleasant temperatures in the range of 46.4°F (8°C) and 60.8°F (16°C) make desirable touring the beautiful parks under the mildly cloudy skies. Weather in October »

November temperatures cool down considerably, to a mildly low range of 41°F (5°C) and 51.8°F (11°C) bringing along high rainfall of up to 5.7" (144.8mm) precipitation. Weather in November »

Winter sets in December with the highest humidity of 81% and extremely low temperatures in the range of 35.6°F (2°C) and 46.4°F (8°C) making Seattle cold and an icy city with the constantly blowing winds. Weather in December »

How many days does it rain in Seattle?

In Seattle, Washington, during the entire year, the rain falls for 152 days and collects up to 37.5" (952.4mm) of precipitation.

When does it snow in Seattle?

Months with snowfall in Seattle, Washington, are January through March, November and December.

How many days does it snow in Seattle?

Throughout the year, there are 4.6 snowfall days, and 6.8" (172.8mm) of snow is accumulated.

What is the month with the lowest UV index in Seattle?

January, November and December, with an average maximum UV index of 1, are months with the lowest UV index in Seattle, Washington.

When does it snow the most in Seattle?

Months with the most snowfall are February and December, with an average 1.7" (43.2mm) of accumulated snow.

When is the ocean coldest in Seattle?

February is the month with the coldest seawater, with an average ocean temperature of 45.3°F (7.4°C). Swimming in 45.3°F (7.4°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

When are the longest days in Seattle?

With an average of 15.9h of daylight, June has the longest days of the year in Seattle, Washington.

When is the highest UV index in Seattle?

June and July, with an average maximum UV index of 7, are months with the highest UV index in Seattle.

What is the least humid month in Seattle?

July is the least humid month in Seattle, Washington, with an average relative humidity of 65.4%.

What is the driest month in Seattle?

The month with the least rainfall is July when the rain falls for 5 days and typically collects 0.7" (17.8mm) of precipitation.

What month has the most sunshine in Seattle?

With an average of 10.1h of sunshine, July has the most sunshine of the year.

What is the warmest month in Seattle?

With an average high-temperature of 76.3°F (24.6°C) and an average low-temperature of 55.9°F (13.3°C), August is the warmest month in Seattle, Washington.

When is the ocean warmest in Seattle?

The month with the warmest seawater in Seattle, Washington, is August, with an average ocean temperature of 53.6°F (12°C). Swimming in 53.6°F (12°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

What is the rainiest month in Seattle?

The month with the most rainfall in Seattle is November when the rain falls for 18.4 days and typically aggregates up to 6.6" (166.9mm) of precipitation.

What is the coldest month in Seattle?

The coldest month in Seattle is December, with an average high-temperature of 45.7°F (7.6°C) and an average low-temperature of 35.6°F (2°C).

What is the most humid month in Seattle?

December is the most humid month in Seattle, with an average relative humidity of 80.1%.

What is the month with the shortest days in Seattle?

With an average of 8.5h of daylight, December has the shortest days of the year in Seattle.

What is the month with the least sunshine in Seattle?

December has the least sunshine of the year, with an average of 1.7h of sunshine.
Average temperature - Seattle, WA
Average humidity - Seattle, WA
Average rainfall - Seattle, WA
Average rainfall days - Seattle, WA

The month with the highest number of rainy days is November (18.4 days).
The month with the lowest number of rainy days is August (4.8 days).

Average snowfall - Seattle, WA

Months with the highest snowfall are February and December (1.7").
Months with the lowest snowfall are April, May, June, July, August, September and October (0").

Average snowfall days - Seattle, WA

The month with the highest number of snowfall days is December (1.6 days).
Months with the lowest number of snowfall days are April, May, June, July, August, September and October (0 days).

Average sea temperature - Seattle, WA

The best month for swimming (with the highest average sea temperature) is August (53.5°F).
The coldest month (with the lowest average sea temperature) is February (45.3°F).

Average daylight / Average sunshine - Seattle, WA