S
M
T
W
T
F
S
30
90°
64°
31
92°
68°
1
94°
71°
2
96°
70°
3
97°
72°
4
94°
73°
5
85°
71°
6
82°
63°
7
84°
59°
8
90°
62°
9
91°
69°
10
80°
70°
11
81°
68°
12
83°
69°
13
87°
71°
14
75°
57°
15
88°
52°
16
91°
65°
17
90°
70°
18
80°
63°
19
84°
67°
20
79°
65°
21
74°
64°
22
75°
62°
23
76°
58°
24
72°
56°
25
73°
52°
26
74°
49°
27
78°
53°
28
77°
54°
29
78°
53°
30
75°
48°
1
78°
54°
2
75°
54°
3
69°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Portland
Portland's September 2026 forecast shows daily high temperatures ranging from 69° to 90°, with overnight lows between 48° and 70°. The average high for September is 77° with an average low of 57°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in Portland. See also: October | November | December.
