S
M
T
W
T
F
S
30
85°
46°
31
86°
47°
1
86°
43°
2
78°
42°
3
76°
42°
4
79°
44°
5
82°
47°
6
79°
43°
7
79°
38°
8
72°
41°
9
72°
40°
10
74°
43°
11
77°
39°
12
82°
40°
13
73°
47°
14
81°
51°
15
84°
41°
16
81°
39°
17
72°
38°
18
74°
39°
19
79°
37°
20
79°
43°
21
78°
47°
22
79°
46°
23
75°
44°
24
68°
42°
25
73°
45°
26
75°
45°
27
74°
44°
28
75°
45°
29
73°
45°
30
67°
38°
1
65°
34°
2
64°
33°
3
64°
34°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Lewiston
Lewiston's September 2026 forecast shows daily high temperatures ranging from 64° to 86°, with overnight lows between 33° and 51°. The average high for September is 76° with an average low of 42°. 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 Lewiston. See also: October | November | December.
