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