S
M
T
W
T
F
S
30
91°
71°
31
91°
71°
1
90°
72°
2
91°
71°
3
88°
70°
4
84°
67°
5
84°
66°
6
87°
66°
7
89°
70°
8
90°
70°
9
90°
69°
10
89°
70°
11
90°
70°
12
90°
69°
13
88°
70°
14
89°
66°
15
90°
68°
16
90°
67°
17
89°
68°
18
81°
61°
19
87°
60°
20
81°
60°
21
81°
62°
22
83°
63°
23
83°
64°
24
86°
60°
25
86°
60°
26
79°
58°
27
81°
59°
28
83°
60°
29
81°
64°
30
85°
60°
1
83°
62°
2
83°
62°
3
84°
61°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Johnston
Johnston's September 2026 forecast shows daily high temperatures ranging from 79° to 91°, with overnight lows between 58° and 72°. The average high for September is 86° with an average low of 65°. 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 Johnston. See also: October | November | December.
