S
M
T
W
T
F
S
30
65°
53°
31
66°
52°
1
66°
50°
2
65°
51°
3
65°
50°
4
64°
48°
5
64°
47°
6
65°
47°
7
65°
48°
8
64°
50°
9
65°
50°
10
65°
49°
11
63°
50°
12
62°
49°
13
63°
50°
14
65°
50°
15
64°
49°
16
64°
49°
17
63°
47°
18
59°
48°
19
61°
49°
20
59°
48°
21
Hist. Avg.
60°
49°
22
Hist. Avg.
59°
49°
23
Hist. Avg.
59°
48°
24
Hist. Avg.
59°
48°
25
Hist. Avg.
59°
48°
26
Hist. Avg.
59°
48°
27
Hist. Avg.
58°
48°
28
Hist. Avg.
58°
47°
29
Hist. Avg.
58°
47°
30
Hist. Avg.
58°
47°
1
Hist. Avg.
57°
47°
2
Hist. Avg.
57°
47°
3
Hist. Avg.
57°
47°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Johnstone
Johnstone's September 2026 forecast shows daily high temperatures ranging from 59° to 66°, with overnight lows between 47° and 53°. The average high for September is 64° with an average low of 49°. 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 Johnstone. See also: October | November | December.