S
M
T
W
T
F
S
30
81°
70°
31
91°
70°
1
93°
72°
2
93°
73°
3
93°
72°
4
93°
72°
5
90°
72°
6
84°
63°
7
82°
58°
8
88°
70°
9
78°
63°
10
79°
54°
11
81°
62°
12
83°
62°
13
75°
65°
14
78°
63°
15
74°
54°
16
72°
54°
17
70°
51°
18
71°
53°
19
71°
49°
20
72°
52°
21
75°
51°
22
71°
56°
23
72°
56°
24
77°
55°
25
78°
57°
26
78°
57°
27
76°
56°
28
78°
57°
29
78°
58°
30
76°
56°
1
75°
50°
2
66°
45°
3
63°
42°
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 63° to 88°, with overnight lows between 42° and 70°. The average high for September is 75° with an average low of 56°. 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.
