S
M
T
W
T
F
S
26
63°
46°
27
82°
41°
28
77°
55°
29
68°
53°
30
N/A
1
61°
38°
2
57°
37°
3
62°
46°
4
72°
55°
5
72°
51°
6
63°
42°
7
62°
36°
8
59°
40°
9
68°
46°
10
71°
46°
11
73°
51°
12
74°
52°
13
72°
50°
14
71°
48°
15
73°
53°
16
71°
53°
17
73°
54°
18
78°
55°
19
79°
56°
20
77°
56°
21
80°
55°
22
80°
57°
23
79°
56°
24
76°
54°
25
74°
54°
26
80°
57°
27
79°
57°
28
77°
56°
29
78°
57°
30
75°
55°
31
77°
56°
1
75°
55°
2
77°
58°
3
79°
53°
4
74°
51°
5
75°
51°
6
75°
52°
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 57° to 80°, with overnight lows between 36° and 58°. The average high for May is 73° with an average low of 51°. 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.
