Climate - Seattle (Washington_state)

In Seattle, the climate is sub-oceanic, with quite mild, rainy winters and mild, fairly sunny summers.
The city is located in northwestern United States, in the state of Washington, of which it is the largest city. Although it is surrounded by water, since it lies between the Puget Sound and Lake Washington, Seattle is still 150 kilometers (95 miles) away from the Pacific coast, and it is partially protected by the mountains of the Coastal Chain which lie to the west (where the Olympic National Park is located), so it is less humid than the coastal area (where rainfall is equal to or higher than 2,000 millimeters - 80 inches per year).
And although it is famous in the United States for being damp and cloudy, in summer, when it is protected by the high pressure system of the Pacific, there are many sunny days. However, the rains in the cold half-year are frequent, and often occur in the form of drizzle.
The average temperature of December (which in western United States is often the coldest month) is 5 °C (40.5 °F), that of August is 19 °C (66 °F). Here are the average temperatures at the Tacoma airport.

Although winter is mild enough, there can sometimes be cold waves, sometimes even in November, with lows going down to -10 °C (14 °F) or even below. For example, the temperature dropped to -16 °C (3 °F) in January 1950, to -15 °C (5 °F) in December 1990, and to -13 °C (8.5 °F) in November 1955, January 1957, November 1985, and February 1989.
While rainfall in Seattle is frequent, snow is rare: on average, 17 centimeters (6.8 in) of snow fall per year. However, occasionally there is a moderate snowfall. In December 2008, snow remained on the ground for more than 10 days in a row. Two particularly snowy months were then February 2019, with 50 cm (20 in) in total, and January 1969, with as much as 127 cm (50 in).
In summer, daytime temperatures are generally mild or pleasantly warm. However, there may also be heat waves, which last a few days, with highs around 35 °C (95 °F), and sometimes more. The temperature reached 40.5 °C (105 °F) in July 2009, 38 °C (100 °F) in August 1981, and 37 °C (99 °F) in July 1994.
Precipitation amounts to 950 mm (37.5 in) per year. It is more abundant from November to January, and in any case, it is frequent from October to May. However, as we have said, in summer it is reduced: the summer, in July and August, is pleasant, with cool nights, and quite sunny, with some morning fogs. Here is the average rainfall.

About 2,100 hours of sunshine per year are recorded in Seattle. As mentioned, even though the sky is often cloudy for many months a year, in summer (and even in late spring) the sunshine amount becomes good. Here are the average sunshine hours per day.

In Seattle, the sea is cold all year round, as can be seen in the following table.



Around Seattle, we find very snowy mountains. To the west, we find the aforementioned mountains of the Olympic National Park. About 100 km (62 mi) to the south-east, we find Mount Rainier, a volcano, 4,392 meters (14,411 feet) high, which is the snowiest place in the United States. North-east of Seattle, the Cascade Range (see for example the Mount Baker Ski Area) is very wet as well, and snowy in the winter months.

When to go

The best time to visit Seattle is summer, especially in July and August, since it is the mildest, driest and sunniest period of the year. May, June and September are also acceptable months.

Back to the climate of Washington state.