S
M
T
W
T
F
S
30
80°
54°
31
82°
43°
1
82°
53°
2
83°
49°
3
82°
44°
4
86°
43°
5
86°
52°
6
85°
43°
7
71°
40°
8
76°
41°
9
80°
42°
10
82°
49°
11
81°
49°
12
83°
46°
13
74°
42°
14
72°
43°
15
79°
50°
16
83°
50°
17
82°
50°
18
81°
48°
19
78°
47°
20
75°
42°
21
77°
47°
22
67°
44°
23
67°
38°
24
69°
44°
25
68°
39°
26
70°
41°
27
71°
42°
28
66°
34°
29
63°
32°
30
61°
32°
1
61°
33°
2
62°
31°
3
64°
35°
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 83°, with overnight lows between 31° and 50°. The average high for September is 73° 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.
