S
M
T
W
T
F
S
30
99°
73°
31
100°
73°
1
97°
76°
2
100°
75°
3
86°
75°
4
93°
79°
5
97°
73°
6
90°
74°
7
95°
75°
8
98°
74°
9
94°
74°
10
96°
76°
11
99°
77°
12
97°
76°
13
95°
74°
14
96°
73°
15
96°
72°
16
94°
71°
17
96°
73°
18
93°
72°
19
88°
65°
20
91°
69°
21
91°
70°
22
91°
69°
23
90°
69°
24
86°
68°
25
82°
68°
26
87°
67°
27
87°
68°
28
86°
68°
29
87°
67°
30
84°
63°
1
80°
58°
2
78°
57°
3
78°
57°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Caldwell
Caldwell's September 2026 forecast shows daily high temperatures ranging from 78° to 99°, with overnight lows between 57° and 77°. The average high for September is 90° with an average low of 69°. 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 Caldwell. See also: October | November | December.
