S
M
T
W
T
F
S
29
46°
41°
30
46°
33°
1
45°
33°
2
43°
36°
3
47°
36°
4
44°
34°
5
41°
35°
6
42°
36°
7
43°
37°
8
44°
36°
9
45°
37°
10
43°
35°
11
42°
35°
12
42°
32°
13
43°
29°
14
42°
31°
15
39°
31°
16
39°
30°
17
41°
31°
18
38°
32°
19
40°
31°
20
40°
33°
21
41°
34°
22
42°
36°
23
42°
34°
24
43°
36°
25
42°
36°
26
42°
35°
27
44°
36°
28
42°
33°
29
43°
34°
30
43°
35°
31
42°
35°
1
43°
36°
2
43°
35°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Issaquah
Issaquah's December 2026 forecast shows daily high temperatures ranging from 38° to 47°, with overnight lows between 29° and 41°. The average high for December is 42° with an average low of 34°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how December weather will actually feel in Issaquah. See also: January | February | March.
