S
M
T
W
T
F
S
30
82°
61°
31
81°
60°
1
80°
56°
2
73°
54°
3
73°
55°
4
74°
52°
5
73°
52°
6
77°
60°
7
80°
59°
8
75°
59°
9
73°
58°
10
77°
58°
11
79°
57°
12
78°
58°
13
79°
59°
14
80°
48°
15
71°
48°
16
69°
49°
17
71°
48°
18
70°
47°
19
68°
48°
20
69°
50°
21
76°
53°
22
76°
54°
23
75°
46°
24
75°
44°
25
69°
44°
26
69°
46°
27
73°
51°
28
73°
51°
29
72°
43°
30
69°
42°
1
66°
42°
2
66°
45°
3
71°
48°
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 66° to 82°, with overnight lows between 42° and 61°. The average high for September is 74° with an average low of 52°. 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.
