S
M
T
W
T
F
S
26
39°
32°
27
43°
30°
28
48°
32°
29
48°
32°
30
48°
30°
1
48°
28°
2
54°
30°
3
55°
34°
4
52°
34°
5
50°
36°
6
37°
28°
7
55°
23°
8
61°
36°
9
59°
37°
10
63°
34°
11
68°
37°
12
72°
43°
13
70°
45°
14
64°
45°
15
66°
39°
16
64°
45°
17
55°
37°
18
50°
32°
19
52°
32°
20
54°
36°
21
57°
32°
22
54°
34°
23
59°
34°
24
61°
39°
25
63°
43°
26
59°
43°
27
64°
43°
28
75°
45°
29
71°
37°
30
62°
40°
31
66°
43°
1
73°
47°
2
73°
55°
3
72°
56°
4
75°
59°
5
76°
57°
6
74°
58°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Portland
Portland's May 2026 forecast shows daily high temperatures ranging from 62° to 76°, with overnight lows between 37° and 59°. The average high for May is 72° 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 Portland. See also: June | July | August.
