S
M
T
W
T
F
S
30
88°
45°
31
89°
47°
1
90°
49°
2
95°
52°
3
92°
50°
4
86°
50°
5
89°
46°
6
88°
47°
7
86°
49°
8
87°
48°
9
90°
49°
10
90°
49°
11
89°
52°
12
93°
52°
13
94°
46°
14
92°
42°
15
85°
43°
16
85°
45°
17
86°
47°
18
89°
49°
19
93°
48°
20
93°
45°
21
92°
41°
22
89°
40°
23
83°
39°
24
82°
40°
25
81°
38°
26
80°
39°
27
81°
44°
28
84°
45°
29
88°
39°
30
87°
38°
1
Hist. Avg.
83°
40°
2
Hist. Avg.
82°
40°
3
Hist. Avg.
82°
40°
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 80° to 95°, with overnight lows between 38° and 52°. The average high for September is 88° with an average low of 45°. 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.
