S
M
T
W
T
F
S
26
59°
38°
27
69°
37°
28
66°
37°
29
66°
48°
30
64°
48°
1
65°
47°
2
61°
44°
3
59°
39°
4
68°
52°
5
77°
54°
6
67°
46°
7
61°
40°
8
62°
41°
9
64°
47°
10
66°
47°
11
67°
46°
12
67°
45°
13
68°
47°
14
66°
45°
15
67°
50°
16
68°
49°
17
68°
49°
18
69°
54°
19
76°
54°
20
75°
53°
21
71°
54°
22
76°
52°
23
72°
53°
24
76°
53°
25
71°
48°
26
70°
51°
27
70°
55°
28
74°
57°
29
78°
57°
30
77°
56°
31
77°
55°
1
74°
50°
2
70°
50°
3
70°
51°
4
72°
50°
5
72°
51°
6
73°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Allentown
Allentown's May 2026 forecast shows daily high temperatures ranging from 59° to 78°, with overnight lows between 39° and 57°. The average high for May is 70° with an average low of 50°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in Allentown. See also: June | July | August.
