S
M
T
W
T
F
S
30
86°
61°
31
84°
61°
1
87°
63°
2
81°
60°
3
81°
59°
4
86°
58°
5
88°
60°
6
90°
62°
7
90°
61°
8
86°
58°
9
88°
60°
10
83°
56°
11
78°
54°
12
77°
54°
13
75°
48°
14
74°
47°
15
75°
47°
16
78°
52°
17
85°
58°
18
74°
55°
19
73°
49°
20
73°
52°
21
75°
48°
22
73°
46°
23
74°
47°
24
75°
48°
25
77°
53°
26
76°
49°
27
71°
40°
28
68°
40°
29
66°
38°
30
66°
42°
1
68°
45°
2
72°
46°
3
73°
44°
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 90°, with overnight lows between 38° and 63°. The average high for September is 78° 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.
