S
M
T
W
T
F
S
30
84°
64°
31
87°
64°
1
87°
63°
2
86°
63°
3
87°
62°
4
86°
63°
5
86°
62°
6
85°
56°
7
85°
53°
8
75°
56°
9
76°
59°
10
74°
60°
11
83°
59°
12
80°
61°
13
83°
58°
14
83°
50°
15
77°
52°
16
71°
50°
17
72°
49°
18
73°
53°
19
75°
47°
20
71°
47°
21
70°
51°
22
72°
55°
23
77°
55°
24
79°
56°
25
79°
56°
26
78°
54°
27
79°
55°
28
76°
51°
29
75°
50°
30
75°
50°
1
74°
49°
2
77°
52°
3
68°
41°
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 68° to 87°, with overnight lows between 41° and 64°. The average high for September is 78° with an average low of 55°. 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.
