S
M
T
W
T
F
S
30
87°
75°
31
87°
80°
1
90°
70°
2
90°
79°
3
91°
79°
4
90°
79°
5
90°
80°
6
90°
79°
7
90°
79°
8
90°
80°
9
92°
80°
10
91°
82°
11
91°
81°
12
93°
80°
13
91°
78°
14
91°
78°
15
90°
81°
16
91°
79°
17
90°
79°
18
89°
79°
19
89°
77°
20
89°
76°
21
90°
77°
22
90°
81°
23
91°
80°
24
90°
81°
25
91°
81°
26
91°
81°
27
91°
81°
28
90°
80°
29
90°
79°
30
89°
78°
1
90°
79°
2
86°
81°
3
86°
81°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in St John
St John's September 2026 forecast shows daily high temperatures ranging from 86° to 91°, with overnight lows between 78° and 81°. The average high for September is 90° with an average low of 80°. 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 John. See also: October | November | December.
