S
M
T
W
T
F
S
30
72°
63°
31
91°
64°
1
86°
55°
2
90°
61°
3
88°
60°
4
85°
70°
5
89°
65°
6
90°
61°
7
86°
64°
8
77°
67°
9
84°
55°
10
81°
47°
11
88°
58°
12
78°
49°
13
71°
40°
14
69°
37°
15
74°
46°
16
75°
41°
17
73°
51°
18
61°
49°
19
63°
46°
20
62°
39°
21
61°
33°
22
61°
33°
23
62°
39°
24
68°
46°
25
67°
47°
26
65°
45°
27
62°
46°
28
64°
48°
29
63°
46°
30
64°
45°
1
60°
38°
2
56°
42°
3
58°
44°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Mercer
Mercer's September 2026 forecast shows daily high temperatures ranging from 56° to 68°, with overnight lows between 33° and 49°. The average high for September is 62° with an average low of 43°. 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 Mercer. See also: October | November | December.
