S
M
T
W
T
F
S
30
83°
56°
31
88°
48°
1
86°
66°
2
59°
52°
3
61°
45°
4
70°
39°
5
75°
45°
6
75°
45°
7
82°
41°
8
88°
54°
9
98°
62°
10
93°
57°
11
90°
52°
12
76°
49°
13
84°
47°
14
88°
46°
15
86°
45°
16
82°
44°
17
81°
46°
18
85°
45°
19
85°
46°
20
83°
47°
21
88°
44°
22
82°
44°
23
84°
48°
24
85°
48°
25
84°
46°
26
81°
47°
27
81°
44°
28
82°
44°
29
79°
40°
30
80°
43°
1
86°
46°
2
87°
46°
3
85°
45°
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 76° to 98°, with overnight lows between 40° and 62°. The average high for September is 85° with an average low of 47°. 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.
