S
M
T
W
T
F
S
30
77°
51°
31
89°
52°
1
80°
59°
2
75°
57°
3
68°
52°
4
72°
52°
5
74°
49°
6
71°
49°
7
72°
55°
8
77°
51°
9
84°
53°
10
88°
53°
11
77°
57°
12
82°
52°
13
64°
52°
14
70°
52°
15
66°
49°
16
79°
50°
17
71°
51°
18
80°
52°
19
81°
55°
20
85°
54°
21
87°
55°
22
79°
57°
23
81°
51°
24
89°
59°
25
69°
50°
26
67°
50°
27
67°
46°
28
70°
46°
29
74°
49°
30
71°
48°
1
66°
47°
2
69°
47°
3
69°
49°
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 66° to 89°, with overnight lows between 46° and 59°. The average high for September is 72° with an average low of 49°. 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.
