S
M
T
W
T
F
S
30
84°
56°
31
79°
56°
1
75°
57°
2
77°
62°
3
77°
56°
4
80°
63°
5
77°
63°
6
82°
57°
7
80°
56°
8
73°
55°
9
75°
54°
10
73°
60°
11
75°
54°
12
78°
54°
13
72°
53°
14
71°
59°
15
75°
60°
16
77°
51°
17
79°
50°
18
70°
50°
19
69°
51°
20
69°
50°
21
70°
52°
22
67°
51°
23
67°
52°
24
68°
54°
25
70°
53°
26
73°
56°
27
73°
52°
28
74°
47°
29
66°
47°
30
66°
52°
1
65°
53°
2
70°
54°
3
70°
52°
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 65° to 84°, with overnight lows between 47° and 63°. The average high for September is 73° with an average low of 54°. 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.
