Average data for 10 years
1 September
Monday
+29°
+12°
2 September
Tuesday
+29°
+13°
3 September
Wednesday
+29°
+12°
4 September
Thursday
+29°
+13°
5 September
Friday
+29°
+12°
6 September
Saturday
+28°
+12°
7 September
Sunday
+28°
+11°
8 September
Monday
+28°
+12°
9 September
Tuesday
+27°
+11°
10 September
Wednesday
+27°
+11°
11 September
Thursday
+27°
+10°
12 September
Friday
+27°
+11°
13 September
Saturday
+27°
+11°
14 September
Sunday
+27°
+11°
15 September
Monday
+27°
+11°
16 September
Tuesday
+26°
+11°
17 September
Wednesday
+25°
+10°
18 September
Thursday
+25°
+10°
19 September
Friday
+24°
+9°
20 September
Saturday
+23°
+8°
21 September
Sunday
+23°
+8°
22 September
Monday
+23°
+8°
23 September
Tuesday
+24°
+8°
24 September
Wednesday
+24°
+9°
25 September
Thursday
+25°
+9°
26 September
Friday
+25°
+9°
27 September
Saturday
+25°
+8°
28 September
Sunday
+25°
+8°
29 September
Monday
+24°
+8°
30 September
Tuesday
+24°
+8°
In September, the weather in Boise is typically warm. Average daily high temperature in September is about 26 degrees above zero. On average, Boise has 22 sunny, 4 partly cloudy, 3 rainy, and 1 cloudy day in September. The rains are usually light. September as well as June is considered the most comfortable time to visit Boise.