S
M
T
W
T
F
S
30
105°
77°
31
104°
74°
1
100°
70°
2
103°
75°
3
104°
79°
4
101°
74°
5
102°
77°
6
99°
74°
7
101°
77°
8
103°
76°
9
92°
68°
10
86°
69°
11
96°
69°
12
100°
69°
13
96°
62°
14
84°
58°
15
80°
60°
16
85°
62°
17
87°
64°
18
84°
61°
19
83°
62°
20
82°
56°
21
87°
63°
22
87°
62°
23
86°
62°
24
81°
61°
25
76°
61°
26
81°
60°
27
83°
61°
28
81°
61°
29
75°
57°
30
81°
48°
1
69°
46°
2
70°
45°
3
69°
46°
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 69° to 103°, with overnight lows between 45° and 77°. The average high for September is 85° with an average low of 61°. 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.
