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
71°
47°
17
72°
47°
18
63°
50°
19
65°
46°
20
66°
43°
21
61°
43°
22
63°
42°
23
68°
47°
24
69°
50°
25
66°
49°
26
68°
49°
27
67°
50°
28
66°
48°
29
61°
39°
30
64°
46°
1
65°
45°
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 72°, with overnight lows between 39° and 50°. The average high for September is 65° with an average low of 46°. 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.
