S
M
T
W
T
F
S
30
98°
77°
31
97°
75°
1
98°
74°
2
99°
75°
3
99°
73°
4
99°
71°
5
100°
72°
6
99°
70°
7
94°
69°
8
91°
67°
9
92°
66°
10
86°
61°
11
87°
58°
12
87°
58°
13
84°
59°
14
85°
61°
15
85°
62°
16
86°
61°
17
86°
62°
18
85°
62°
19
86°
61°
20
85°
61°
21
85°
60°
22
84°
61°
23
84°
60°
24
83°
59°
25
83°
59°
26
82°
57°
27
83°
58°
28
83°
58°
29
82°
57°
30
83°
58°
1
82°
57°
2
82°
57°
3
81°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in St. Joseph
St. Joseph's September 2026 forecast shows daily high temperatures ranging from 81° to 100°, with overnight lows between 56° and 75°. The average high for September is 88° with an average low of 62°. 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 St. Joseph. See also: October | November | December.
