S
M
T
W
T
F
S
30
100°
75°
31
100°
75°
1
100°
75°
2
99°
76°
3
91°
76°
4
98°
75°
5
99°
75°
6
99°
75°
7
101°
78°
8
100°
77°
9
99°
76°
10
99°
78°
11
99°
77°
12
101°
76°
13
100°
75°
14
98°
74°
15
93°
70°
16
93°
70°
17
93°
71°
18
91°
70°
19
90°
66°
20
87°
64°
21
91°
70°
22
91°
70°
23
90°
69°
24
89°
68°
25
83°
68°
26
88°
67°
27
88°
67°
28
87°
66°
29
86°
67°
30
84°
61°
1
77°
55°
2
76°
56°
3
76°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Princeton
Princeton's September 2026 forecast shows daily high temperatures ranging from 76° to 101°, with overnight lows between 55° and 78°. The average high for September is 91° with an average low of 69°. 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 Princeton. See also: October | November | December.
