How cold is it in Washington State?
The lowest temperature recorded in Washington State is −48 °F /−44 °C, a record set in both in Winthrop and Mazama in Eastern Washington. Western Washington has milder winters due to its proximity to the Pacific Ocean.
In Western Washington, the winters are characterized by fog, overcast skies and long-lasting drizzles rather than extreme cold spells or plenty of snow. The lowest recorded temperature as just −6 °F / −21 °C, a record set in Longview.
Are the summers cold in Washington State?
Generally speaking, Eastern Washington have more extreme summer temperatures than Western Washington, with heat waves being more common. The record for highest temperature in Washington State (118 °F / 48 °C) is from Ice Harbor Dam, a hydroelectric dam on the Snake River in Eastern Washington.
Western Washington tend to have milder summers, but the heat record is not much lower than for Eastern Washington: 105 °F / 41 °C in Aberdeen.
Temperatures
Data for Washington State 1895-2015
| Month | Jan | Feb | Mar | Apr | May | Jun |
| Record high
°F (°C) |
74 (23) |
83 (28) |
95 (35) |
103 (39) |
107 (42) |
113 (45) |
| Mean maximum
°F (°C) |
60 (16) |
64 (18) |
73 (23) |
86 (30) |
94 (34) |
102 (39) |
| Average high
°F (°C) |
34.8 (1.6) |
40.6 (4.8) |
47.7 (8.7) |
55.9 (13.3) |
63.6 (17.6) |
69.9 (21.1) |
| Average low
°F (°C) |
23.0 (−5) |
26.0 (−3.3) |
29.6 (−1.3) |
34.2 (1.2) |
40.1 (4.5) |
45.7 (7.6) |
| Mean minimum
°F (°C) |
−19 (−28) |
−8 (−22) |
−2 (−19) |
14 (−10) |
21 (−6) |
26 (−3) |
| Record low
°F (°C) |
−42 (−41) |
−40 (−40) |
−25 (−32) |
−7 (−22) |
11 (−12) |
20 (−7) |
| Month | Jul | Aug | Sep | Oct | Nov | Dec |
| Record high
°F (°C) |
118 (48) |
118 (48) |
111 (44) |
99 (37) |
83 (28) |
74 (23) |
| Mean maximum
°F (°C) |
109 (43) |
106 (41) |
98 (37) |
84 (29) |
67 (19) |
60 (16) |
| Average high
°F (°C) |
78.0 (25.6) |
77.3 (25.2) |
69.4 (20.8) |
57.2 (14) |
43.2 (6.2) |
36.2 (2.3) |
| Average low
°F (°C) |
50.5 (10.3) |
50.0 (10) |
44.7 (7.1) |
37.2 (2.9) |
29.9 (−1.2) |
25.3 (−3.7) |
| Mean minimum
°F (°C) |
31 (−1) |
31 (−1) |
24 (−4) |
16 (−9) |
2 (−17) |
−8 (−22) |
| Record low
°F (°C) |
22 (−6) |
20 (−7) |
11 (−12) |
−5 (−21) |
−29 (−34) |
−48 (−44) |
Sources:
- Office of the Washington State Climatologist
- Comparative Data for the Western States. WRCC.
How rainy is Washington State?
Below, you will find a table showing the average precipitation in Washington State, but it really doesn’t show the whole picture since the amount of precipitation varies a lot between different regions of the state.
Generally speaking, Western Washington is much wetter than Eastern Washington. The two regions are divided by the Cascade Mountain range that runs from north to south, and this range prevents a lot of the moist from the Pacific Ocean from reaching farther inland. Therefore, Eastern Washington does not have the marine climate that is so characteristic for Western Washington.
The Olympic Peninsula in Eastern Washington receives approximately 160 inches (4,100 mm) of precipitation in an average year, making it not just the wettest part of Washington State but the wettest part of the 48 contiguous states. There is even a (temperate) rainforest growing here, which is a very rare thing to find in the United States. During some parts of the year, weeks can pass without a single clear day on the peninsula.
If you cross the Cascade Range and enters Eastern Washington, you can get to some of the driest parts of the state. Large parts of Eastern Washington are grasslands or shrub-steppe, or used to be of that nature type before it was converted to farmland.
The driest areas of Eastern Washington are located in the heaviest rain shadow of the Cascades, and some spots here receive no more than 6 inches (150 mm) of precipitation in an average year. The strongest rain shadow effects are to be seen at the comparatively low elevations of the central Columbia Plateau, especially just east of the Columbia River from the Snake River to the Okanagan Highland.
As you continue to move farther eastward in Eastern Washington, the amount of annual precipitation will increase gradually as you get away from the rain shadow.
Average precipitation (inches / millimeters)
Data for Washington State 1895-2015
| Month | Jan | Feb | Mar | Apr | May | Jun |
| Precipitation | 6.08 in
154.4 mm |
4.61 in
117.1 mm |
4.23 in
107.4 mm |
2.87 in
72.9 mm |
2.31 in
58.7 mm |
1.89 in
48 mm |
| Month | Jul | Aug | Sep | Oct | Nov | Dec |
| Precipitation | 0.85 in 21.6 mm |
1.02 in 25.9 mm |
1.93 in 49 mm |
3.67 in 93.2 mm |
6.22 in 158 |
6.52 in 165.6 |
Sources:
- Office of the Washington State Climatologist
- Comparative Data for the Western States. WRCC.
Snowfall
The western slopes of the Cascade Range in Washington State receives some of the heaviest annual snowfall in the 48 contiguous states. In some spots, getting more than 200 inches of snow in a year is not unusual. Mount Baker, located not far from the Canadian border, is one of the snowiest places in the world. In 1999, it hit a new record for snowfall in a single season by getting 1,140 inches (29 meters) of snow.
Along the Pacific Coast, winters tend to be rainy rather than snowy, but there have been many exceptions, including the Big Snow events and Deep Freeze events that occurred now and then until the mid-20th century. The lowest recorded temperature for the port city Seattle is 0 °F (−18 °C), a record set in January 1950.
Wind and pressure systems
The large semi-permanent high pressure and low pressure systems of the northern Pacific Ocean have a major impact on the climate of Washington State, but air masses of the North American continent are also important.
In spring and summer, the northern Pacific Ocean is dominated by a high pressure anticyclone system, where air spirals outwards in a clockwise movement. This means that you can expect winds from the northwest to dominate Washington State during spring and summer, bringing with them fairly cool and dry air. This is especially noticeable on the western side of the Cascade Mountains.
In fall and winter, the northern Pacific Ocean is instead dominated by a low pressure cyclone system where air spirals inwards counter-clockwise. This is what brings the famous Chinook winds to Washington State. The Chinooks of Washington State are wet and warm coastal winds from the southwest that help create the typical wet winter climate of Western Washington. An extreme form of Chinooks known as “The Pineapple Express” are storms that make landfall in Washington and Oregon from October to April.