S
M
T
W
T
F
S
30
75°
53°
31
82°
38°
1
80°
55°
2
76°
51°
3
77°
46°
4
79°
46°
5
82°
46°
6
86°
44°
7
68°
47°
8
76°
34°
9
78°
42°
10
82°
41°
11
81°
58°
12
84°
39°
13
77°
46°
14
66°
42°
15
76°
32°
16
83°
40°
17
75°
56°
18
70°
53°
19
64°
46°
20
68°
41°
21
73°
43°
22
73°
46°
23
76°
41°
24
80°
45°
25
80°
47°
26
73°
46°
27
76°
48°
28
72°
44°
29
71°
43°
30
67°
44°
1
62°
40°
2
72°
33°
3
67°
39°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Idaho Falls
Idaho Falls's September 2026 forecast shows daily high temperatures ranging from 62° to 80°, with overnight lows between 33° and 48°. The average high for September is 72° with an average low of 43°. 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 Idaho Falls. See also: October | November | December.
