S
M
T
W
T
F
S
30
82°
67°
31
91°
70°
1
97°
74°
2
95°
71°
3
92°
73°
4
92°
73°
5
84°
72°
6
79°
66°
7
83°
58°
8
85°
68°
9
78°
66°
10
77°
55°
11
81°
61°
12
83°
64°
13
80°
63°
14
81°
62°
15
73°
57°
16
73°
53°
17
77°
54°
18
76°
56°
19
76°
54°
20
75°
53°
21
74°
58°
22
70°
58°
23
71°
57°
24
77°
58°
25
78°
58°
26
78°
57°
27
77°
58°
28
78°
58°
29
78°
59°
30
77°
58°
1
76°
54°
2
75°
48°
3
63°
44°
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 63° to 85°, with overnight lows between 44° and 68°. The average high for September is 77° with an average low of 57°. 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.
