S
M
T
W
T
F
S
26
71°
29°
27
58°
45°
28
56°
38°
29
70°
35°
30
77°
40°
1
77°
42°
2
75°
44°
3
85°
45°
4
78°
43°
5
64°
47°
6
58°
52°
7
68°
49°
8
62°
44°
9
70°
44°
10
68°
43°
11
74°
43°
12
83°
44°
13
59°
49°
14
60°
47°
15
51°
41°
16
59°
37°
17
64°
32°
18
69°
42°
19
64°
44°
20
69°
46°
21
78°
40°
22
79°
43°
23
68°
46°
24
75°
41°
25
57°
43°
26
65°
41°
27
75°
42°
28
82°
48°
29
66°
43°
30
65°
40°
31
72°
41°
1
81°
47°
2
88°
54°
3
68°
45°
4
68°
44°
5
67°
45°
6
64°
44°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Boston Harbor
Boston Harbor's May 2026 forecast shows daily high temperatures ranging from 64° to 88°, with overnight lows between 40° and 54°. The average high for May is 71° with an average low of 45°. 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 Boston Harbor. See also: June | July | August.
