S
M
T
W
T
F
S
30
71°
61°
31
83°
66°
1
88°
62°
2
82°
63°
3
76°
56°
4
75°
64°
5
78°
52°
6
77°
46°
7
76°
46°
8
74°
52°
9
78°
61°
10
74°
45°
11
74°
41°
12
81°
55°
13
67°
50°
14
66°
38°
15
68°
53°
16
70°
49°
17
69°
50°
18
68°
47°
19
60°
51°
20
67°
46°
21
59°
42°
22
58°
43°
23
60°
45°
24
67°
47°
25
66°
46°
26
65°
44°
27
65°
44°
28
65°
47°
29
67°
48°
30
67°
46°
1
65°
41°
2
59°
46°
3
57°
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 57° to 68°, with overnight lows between 41° and 51°. The average high for September 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 September weather will actually feel in St. Helen. See also: October | November | December.
