S
M
T
W
T
F
S
30
75°
50°
31
78°
48°
1
78°
47°
2
72°
60°
3
67°
60°
4
80°
61°
5
72°
53°
6
72°
50°
7
80°
47°
8
77°
51°
9
68°
44°
10
83°
65°
11
72°
50°
12
74°
39°
13
65°
54°
14
71°
42°
15
69°
49°
16
75°
52°
17
72°
58°
18
75°
46°
19
67°
51°
20
68°
51°
21
63°
46°
22
63°
50°
23
66°
50°
24
67°
49°
25
68°
51°
26
66°
50°
27
60°
52°
28
70°
52°
29
67°
50°
30
61°
48°
1
62°
50°
2
63°
50°
3
67°
51°
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 60° to 75°, with overnight lows between 42° and 58°. The average high for September is 67° with an average low of 50°. 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.
