S
M
T
W
T
F
S
30
88°
80°
31
94°
79°
1
91°
75°
2
90°
79°
3
90°
80°
4
91°
78°
5
90°
79°
6
90°
78°
7
88°
78°
8
90°
79°
9
90°
79°
10
91°
80°
11
90°
81°
12
89°
81°
13
88°
79°
14
88°
79°
15
88°
77°
16
89°
78°
17
93°
76°
18
91°
79°
19
89°
80°
20
91°
79°
21
91°
79°
22
89°
78°
23
89°
79°
24
91°
79°
25
95°
79°
26
95°
79°
27
90°
80°
28
90°
78°
29
89°
79°
30
89°
79°
1
92°
78°
2
89°
78°
3
89°
79°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in San Juan
San Juan's September 2026 forecast shows daily high temperatures ranging from ° to °, with overnight lows between ° and °. The average high for September is ° with an average low of °. 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 San Juan. See also: October | November | December.
