S
M
T
W
T
F
S
30
83°
70°
31
85°
61°
1
80°
65°
2
83°
66°
3
80°
66°
4
79°
63°
5
78°
58°
6
72°
56°
7
74°
59°
8
76°
57°
9
73°
52°
10
77°
59°
11
74°
58°
12
76°
58°
13
76°
57°
14
74°
56°
15
74°
52°
16
65°
52°
17
72°
55°
18
74°
56°
19
75°
56°
20
75°
57°
21
74°
56°
22
75°
53°
23
67°
48°
24
62°
48°
25
67°
52°
26
65°
53°
27
72°
53°
28
72°
52°
29
71°
53°
30
71°
53°
1
70°
51°
2
67°
51°
3
65°
50°
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 62° to 85°, with overnight lows between 48° and 70°. The average high for September is 74° with an average low of 56°. 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.
