S
M
T
W
T
F
S
30
81°
66°
31
87°
67°
1
88°
67°
2
88°
67°
3
88°
69°
4
89°
67°
5
89°
67°
6
83°
61°
7
80°
60°
8
79°
62°
9
78°
56°
10
78°
55°
11
76°
54°
12
75°
52°
13
73°
53°
14
74°
59°
15
80°
56°
16
79°
54°
17
79°
55°
18
80°
56°
19
79°
55°
20
77°
54°
21
79°
56°
22
79°
56°
23
78°
55°
24
78°
54°
25
77°
54°
26
78°
52°
27
77°
53°
28
77°
52°
29
76°
52°
30
76°
52°
1
75°
51°
2
75°
51°
3
74°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mason City
Mason City's September 2026 forecast shows daily high temperatures ranging from 73° to 89°, with overnight lows between 50° and 69°. The average high for September is 79° with an average low of 57°. 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 Mason City. See also: October | November | December.
