S
M
T
W
T
F
S
30
84°
64°
31
86°
67°
1
89°
68°
2
89°
68°
3
88°
66°
4
87°
68°
5
88°
66°
6
84°
67°
7
82°
66°
8
82°
67°
9
86°
62°
10
85°
61°
11
80°
67°
12
85°
65°
13
86°
65°
14
81°
66°
15
86°
65°
16
79°
63°
17
78°
64°
18
Hist. Avg.
80°
59°
19
Hist. Avg.
79°
59°
20
Hist. Avg.
79°
58°
21
Hist. Avg.
78°
58°
22
Hist. Avg.
78°
58°
23
Hist. Avg.
78°
57°
24
Hist. Avg.
77°
57°
25
Hist. Avg.
77°
56°
26
Hist. Avg.
76°
56°
27
Hist. Avg.
76°
55°
28
Hist. Avg.
76°
55°
29
Hist. Avg.
75°
54°
30
Hist. Avg.
75°
54°
1
Hist. Avg.
74°
54°
2
Hist. Avg.
74°
53°
3
Hist. Avg.
74°
52°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Mount Rainier
Mount Rainier's September 2026 forecast shows daily high temperatures ranging from 78° to 89°, with overnight lows between 61° and 68°. The average high for September is 84° with an average low of 66°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Mount Rainier. See also: October | November | December.
