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
75°
49°
24
80°
51°
25
66°
51°
26
65°
45°
27
64°
44°
28
71°
41°
29
76°
45°
30
69°
55°
1
75°
49°
2
80°
51°
3
82°
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 82° to 82°, with overnight lows between 50° and 50°. The average high for September is 82° 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.
