S
M
T
W
T
F
S
30
90°
82°
31
90°
82°
1
89°
82°
2
90°
83°
3
89°
81°
4
88°
81°
5
89°
82°
6
88°
81°
7
88°
82°
8
90°
81°
9
90°
82°
10
89°
83°
11
90°
82°
12
88°
83°
13
90°
80°
14
89°
81°
15
88°
81°
16
88°
80°
17
89°
81°
18
89°
81°
19
90°
80°
20
89°
81°
21
89°
80°
22
88°
79°
23
87°
78°
24
87°
77°
25
88°
80°
26
88°
79°
27
87°
80°
28
88°
80°
29
89°
79°
30
88°
80°
1
87°
80°
2
87°
79°
3
86°
79°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Marathon
Marathon's September 2026 forecast shows daily high temperatures ranging from 86° to 90°, with overnight lows between 77° and 83°. The average high for September is 88° with an average low of 81°. 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 Marathon. See also: October | November | December.
