S
M
T
W
T
F
S
30
81°
56°
31
75°
68°
1
88°
68°
2
N/A
3
88°
69°
4
83°
62°
5
81°
60°
6
76°
57°
7
78°
59°
8
80°
61°
9
82°
66°
10
84°
61°
11
80°
58°
12
78°
59°
13
79°
61°
14
78°
56°
15
77°
57°
16
74°
59°
17
76°
52°
18
72°
51°
19
79°
55°
20
79°
57°
21
78°
55°
22
77°
56°
23
72°
57°
24
77°
53°
25
75°
52°
26
77°
57°
27
77°
56°
28
73°
50°
29
67°
47°
30
68°
49°
1
66°
45°
2
66°
50°
3
65°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Allentown
Allentown's September 2026 forecast shows daily high temperatures ranging from 65° to 88°, with overnight lows between 45° and 69°. The average high for September is 76° with an average low of 56°. 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 Allentown. See also: October | November | December.
