S
M
T
W
T
F
S
30
81°
65°
31
83°
68°
1
90°
69°
2
91°
73°
3
86°
68°
4
77°
67°
5
79°
59°
6
77°
54°
7
78°
52°
8
81°
56°
9
75°
68°
10
78°
56°
11
77°
49°
12
84°
62°
13
74°
51°
14
70°
44°
15
76°
61°
16
70°
60°
17
72°
52°
18
71°
53°
19
66°
56°
20
69°
58°
21
69°
56°
22
70°
52°
23
71°
53°
24
72°
54°
25
72°
52°
26
73°
53°
27
72°
52°
28
68°
48°
29
73°
55°
30
71°
54°
1
74°
54°
2
74°
51°
3
71°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in St. Johns
St. Johns's September 2026 forecast shows daily high temperatures ranging from 66° to 76°, with overnight lows between 48° and 61°. The average high for September is 71° with an average low of 54°. 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. Johns. See also: October | November | December.
