S
M
T
W
T
F
S
30
78°
52°
31
78°
56°
1
77°
55°
2
77°
48°
3
76°
45°
4
68°
46°
5
69°
54°
6
71°
53°
7
76°
48°
8
69°
46°
9
68°
45°
10
69°
52°
11
67°
53°
12
75°
53°
13
75°
51°
14
74°
50°
15
73°
43°
16
67°
47°
17
65°
43°
18
66°
41°
19
65°
40°
20
63°
38°
21
61°
40°
22
63°
48°
23
63°
41°
24
64°
39°
25
62°
47°
26
67°
47°
27
65°
48°
28
70°
42°
29
69°
41°
30
60°
41°
1
61°
43°
2
67°
43°
3
62°
46°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in St. Helen
St. Helen's September 2026 forecast shows daily high temperatures ranging from 60° to 78°, with overnight lows between 38° and 56°. The average high for September is 69° 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 September weather will actually feel in St. Helen. See also: October | November | December.
