S
M
T
W
T
F
S
30
81°
60°
31
81°
60°
1
80°
59°
2
78°
59°
3
80°
58°
4
80°
59°
5
79°
58°
6
80°
59°
7
81°
60°
8
79°
58°
9
78°
57°
10
78°
57°
11
79°
56°
12
76°
56°
13
76°
55°
14
67°
44°
15
67°
53°
16
69°
51°
17
68°
49°
18
69°
48°
19
73°
50°
20
76°
52°
21
75°
53°
22
73°
45°
23
74°
41°
24
69°
42°
25
70°
50°
26
70°
46°
27
67°
39°
28
66°
39°
29
63°
44°
30
68°
48°
1
64°
47°
2
68°
50°
3
70°
50°
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 81°, with overnight lows between 39° and 60°. The average high for September is 73° 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.
