S
M
T
W
T
F
S
30
72°
56°
31
74°
62°
1
76°
63°
2
77°
63°
3
74°
61°
4
72°
60°
5
71°
58°
6
71°
57°
7
70°
60°
8
73°
59°
9
69°
56°
10
68°
53°
11
73°
48°
12
65°
47°
13
68°
51°
14
67°
50°
15
64°
47°
16
66°
46°
17
65°
48°
18
67°
51°
19
65°
48°
20
64°
47°
21
62°
47°
22
64°
51°
23
68°
47°
24
68°
45°
25
69°
53°
26
70°
53°
27
69°
51°
28
62°
46°
29
65°
49°
30
68°
42°
1
61°
49°
2
67°
51°
3
68°
42°
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 61° to 77°, with overnight lows between 42° and 63°. The average high for September is 68° with an average low of 52°. 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.
