S
M
T
W
T
F
S
30
88°
81°
31
87°
82°
1
87°
82°
2
88°
81°
3
87°
82°
4
87°
81°
5
88°
82°
6
87°
82°
7
87°
81°
8
88°
81°
9
88°
80°
10
87°
81°
11
87°
81°
12
88°
80°
13
87°
81°
14
87°
81°
15
88°
80°
16
86°
82°
17
87°
81°
18
86°
81°
19
87°
80°
20
87°
80°
21
86°
81°
22
87°
81°
23
88°
80°
24
87°
80°
25
88°
79°
26
89°
79°
27
90°
78°
28
89°
80°
29
90°
79°
30
90°
79°
1
89°
80°
2
90°
80°
3
90°
79°
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 90°, with overnight lows between 78° and 82°. The average high for September is 88° with an average low of 81°. 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.
