S
M
T
W
T
F
S
30
75°
58°
31
86°
65°
1
89°
71°
2
92°
70°
3
87°
68°
4
79°
66°
5
80°
57°
6
74°
53°
7
78°
53°
8
81°
67°
9
84°
66°
10
73°
53°
11
73°
52°
12
81°
60°
13
81°
60°
14
75°
53°
15
75°
53°
16
72°
50°
17
73°
51°
18
72°
49°
19
69°
48°
20
78°
54°
21
76°
53°
22
71°
52°
23
70°
52°
24
75°
51°
25
76°
52°
26
76°
51°
27
74°
50°
28
75°
52°
29
76°
52°
30
76°
51°
1
75°
51°
2
72°
45°
3
71°
42°
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 69° to 84°, with overnight lows between 42° and 67°. The average high for September is 75° with an average low of 53°. 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.
