Seattle |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual |
Avg. Temperature |
4.5 |
6.4 |
7.6 |
9.6 |
12.8 |
16.1 |
18.4 |
18.6 |
15.9 |
11.6 |
7.4 |
4.7 |
11.1 |
Avg. Max Temperature |
7.2 |
9.7 |
11.5 |
14.0 |
17.7 |
21.1 |
24.0 |
24.0 |
20.7 |
15.4 |
10.3 |
7.3 |
15.2 |
Avg. Min Temperature |
1.8 |
3.0 |
3.6 |
5.1 |
7.9 |
11.1 |
12.9 |
13.2 |
11.1 |
7.7 |
4.5 |
2.1 |
7.0 |
Days with Max Temp of 32
C or Higher |
0.0 |
0.0 |
0.0 |
0.0 |
< 0.5 |
< 0.5 |
1.0 |
1.0 |
< 0.5 |
0.0 |
0.0 |
0.0 |
2.0 |
Days with Min Temp Below
Freezing |
10.0 |
6.0 |
3.0 |
< 0.5 |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
< 0.5 |
3.0 |
9.0 |
30.0 |
|
|
Seattle Sea-tac
Airport Heating and
Cooling |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual |
Heating Degree Days |
772 |
602 |
601 |
474 |
307 |
144 |
58.0 |
65.0 |
156 |
378 |
591 |
760 |
4908 |
Cooling Degree Days |
0.0 |
0.0 |
0.0 |
0.0 |
0.0 |
21.0 |
64.0 |
81.0 |
24.0 |
0.0 |
0.0 |
0.0 |
190 |
|
|
Seattle Sea-tac
Airport Precipitation |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual |
Precipitation (inches) |
5.4 |
4.0 |
3.5 |
2.3 |
1.7 |
1.5 |
0.8 |
1.1 |
1.9 |
3.2 |
5.8 |
5.9 |
37.2 |
Days with Precipitation
0.01 inch or More |
19.0 |
16.0 |
17.0 |
14.0 |
10.0 |
9.0 |
5.0 |
6.0 |
9.0 |
13.0 |
18.0 |
19.0 |
155 |
Monthly Snowfall
(inches) |
4.9 |
1.6 |
1.3 |
0.1 |
< 0.05 |
0.0 |
< 0.05 |
0.0 |
< 0.05 |
0.0 |
1.1 |
2.4 |
11.4 |
|
|
Other Seattle Sea-tac
Airport Weather
Indicators |
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Annual |
Average Wind Speed |
9.6 |
9.5 |
9.5 |
9.4 |
8.9 |
8.7 |
8.2 |
7.8 |
8.1 |
8.5 |
9.3 |
9.6 |
8.9 |
Clear Days |
3.0 |
3.0 |
3.0 |
3.0 |
4.0 |
5.0 |
10.0 |
9.0 |
8.0 |
4.0 |
2.0 |
2.0 |
58.0 |
Partly Cloudy Days |
4.0 |
4.0 |
6.0 |
7.0 |
9.0 |
8.0 |
10.0 |
10.0 |
9.0 |
7.0 |
4.0 |
4.0 |
82.0 |
Cloudy Days |
24.0 |
21.0 |
22.0 |
20.0 |
18.0 |
17.0 |
11.0 |
12.0 |
13.0 |
19.0 |
23.0 |
25.0 |
226 |
Percent of Possible
Sunshine |
28.0 |
40.0 |
50.0 |
52.0 |
56.0 |
56.0 |
65.0 |
65.0 |
62.0 |
43.0 |
28.0 |
23.0 |
47.0 |
Avg. Relative Humidity |
60.0 |
77.0 |
75.0 |
72.5 |
70.5 |
69.0 |
67.0 |
66.0 |
68.0 |
72.0 |
75.5 |
78.5 |
80.5 |