S
M
T
W
T
F
S
30
96°
72°
31
99°
73°
1
100°
79°
2
100°
82°
3
99°
82°
4
100°
81°
5
101°
82°
6
90°
65°
7
89°
63°
8
94°
73°
9
100°
71°
10
82°
67°
11
82°
68°
12
89°
69°
13
87°
65°
14
83°
63°
15
88°
67°
16
86°
68°
17
86°
67°
18
79°
60°
19
80°
65°
20
83°
65°
21
84°
65°
22
78°
64°
23
80°
63°
24
83°
64°
25
84°
65°
26
84°
65°
27
83°
64°
28
83°
65°
29
82°
65°
30
83°
63°
1
79°
57°
2
69°
52°
3
68°
50°
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 68° to 100°, with overnight lows between 50° and 73°. The average high for September is 84° with an average low of 64°. 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.
