S
M
T
W
T
F
S
26
57°
46°
27
68°
38°
28
66°
47°
29
61°
49°
30
65°
41°
1
67°
37°
2
60°
42°
3
63°
37°
4
74°
41°
5
80°
43°
6
75°
58°
7
63°
45°
8
71°
33°
9
75°
43°
10
80°
40°
11
60°
40°
12
73°
35°
13
74°
45°
14
56°
42°
15
69°
47°
16
81°
59°
17
87°
59°
18
91°
62°
19
91°
65°
20
85°
60°
21
69°
46°
22
68°
51°
23
72°
52°
24
75°
54°
25
76°
56°
26
78°
59°
27
84°
52°
28
76°
56°
29
77°
58°
30
78°
57°
31
73°
53°
1
71°
52°
2
71°
52°
3
72°
50°
4
72°
51°
5
77°
58°
6
80°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Harriston
Harriston's May 2026 forecast shows daily high temperatures ranging from 56° to 91°, with overnight lows between 42° and 65°. The average high for May is 76° with an average low of 55°. 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 Harriston. See also: June | July | August.
