S
M
T
W
T
F
S
26
67°
38°
27
73°
37°
28
69°
48°
29
58°
44°
30
50°
38°
1
53°
30°
2
50°
36°
3
59°
36°
4
70°
44°
5
71°
45°
6
55°
39°
7
56°
38°
8
55°
39°
9
61°
46°
10
57°
40°
11
58°
39°
12
55°
40°
13
56°
45°
14
63°
44°
15
61°
46°
16
59°
47°
17
63°
43°
18
62°
57°
19
65°
45°
20
67°
50°
21
70°
50°
22
68°
49°
23
62°
42°
24
60°
43°
25
61°
43°
26
62°
45°
27
62°
44°
28
63°
43°
29
63°
44°
30
66°
46°
31
65°
51°
1
66°
48°
2
67°
46°
3
70°
52°
4
70°
50°
5
68°
54°
6
76°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Ottawa
Ottawa's May 2026 forecast shows daily high temperatures ranging from 55° to 76°, with overnight lows between 38° and 57°. The average high for May is 63° with an average low of 46°. 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 Ottawa. See also: June | July | August.
