S
M
T
W
T
F
S
30
84°
64°
31
90°
65°
1
92°
72°
2
93°
71°
3
93°
73°
4
95°
72°
5
92°
71°
6
82°
63°
7
82°
58°
8
86°
70°
9
88°
67°
10
79°
54°
11
82°
61°
12
81°
65°
13
85°
65°
14
83°
60°
15
75°
53°
16
72°
53°
17
78°
57°
18
78°
57°
19
79°
54°
20
67°
43°
21
80°
59°
22
74°
59°
23
74°
58°
24
81°
59°
25
81°
59°
26
80°
58°
27
81°
59°
28
81°
60°
29
80°
60°
30
81°
59°
1
76°
55°
2
74°
48°
3
66°
45°
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 66° to 88°, with overnight lows between 43° and 70°. The average high for September is 79° with an average low of 58°. 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.
