S
M
T
W
T
F
S
30
81°
53°
31
82°
54°
1
84°
55°
2
85°
59°
3
88°
62°
4
91°
62°
5
91°
57°
6
88°
53°
7
85°
58°
8
87°
53°
9
76°
47°
10
75°
53°
11
77°
57°
12
82°
60°
13
78°
59°
14
75°
49°
15
74°
48°
16
Hist. Avg.
80°
53°
17
Hist. Avg.
80°
52°
18
Hist. Avg.
79°
52°
19
Hist. Avg.
79°
52°
20
Hist. Avg.
78°
51°
21
Hist. Avg.
78°
51°
22
Hist. Avg.
77°
51°
23
Hist. Avg.
77°
50°
24
Hist. Avg.
76°
50°
25
Hist. Avg.
76°
50°
26
Hist. Avg.
76°
49°
27
Hist. Avg.
75°
49°
28
Hist. Avg.
75°
49°
29
Hist. Avg.
74°
48°
30
Hist. Avg.
74°
48°
1
Hist. Avg.
73°
47°
2
Hist. Avg.
72°
47°
3
Hist. Avg.
72°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Boise
Boise's September 2026 forecast shows daily high temperatures ranging from 74° to 91°, with overnight lows between 47° and 62°. The average high for September is 82° with an average low of 55°. 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 Boise. See also: October | November | December.
