S
M
T
W
T
F
S
30
98°
68°
31
99°
65°
1
96°
64°
2
95°
63°
3
96°
65°
4
97°
64°
5
95°
61°
6
95°
60°
7
93°
61°
8
93°
65°
9
91°
63°
10
90°
58°
11
90°
57°
12
91°
62°
13
90°
63°
14
89°
60°
15
89°
56°
16
87°
55°
17
86°
55°
18
87°
56°
19
87°
56°
20
88°
55°
21
86°
57°
22
87°
59°
23
89°
61°
24
89°
61°
25
92°
59°
26
92°
61°
27
91°
62°
28
92°
61°
29
93°
61°
30
92°
62°
1
92°
61°
2
91°
60°
3
92°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in San Bernardino
San Bernardino's September 2026 forecast shows daily high temperatures ranging from 86° to 99°, with overnight lows between 55° and 68°. The average high for September is 91° with an average low of 60°. 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 San Bernardino. See also: October | November | December.
