S
M
T
W
T
F
S
26
63°
34°
27
73°
36°
28
72°
46°
29
71°
50°
30
52°
41°
1
55°
36°
2
52°
36°
3
49°
36°
4
69°
44°
5
78°
55°
6
55°
42°
7
58°
34°
8
53°
32°
9
54°
31°
10
65°
38°
11
56°
31°
12
56°
31°
13
57°
51°
14
55°
47°
15
64°
46°
16
76°
56°
17
73°
45°
18
72°
61°
19
80°
63°
20
67°
45°
21
63°
46°
22
64°
48°
23
66°
49°
24
63°
48°
25
64°
51°
26
65°
49°
27
66°
47°
28
65°
46°
29
66°
53°
30
66°
54°
31
69°
52°
1
67°
51°
2
66°
48°
3
66°
47°
4
66°
47°
5
69°
56°
6
70°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Waltham
Waltham's May 2026 forecast shows daily high temperatures ranging from 55° to 80°, with overnight lows between 45° and 63°. The average high for May is 67° 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 Waltham. See also: June | July | August.
