S
M
T
W
T
F
S
30
82°
68°
31
88°
55°
1
84°
60°
2
85°
66°
3
91°
66°
4
83°
61°
5
82°
66°
6
82°
67°
7
86°
65°
8
82°
54°
9
78°
47°
10
80°
64°
11
85°
54°
12
71°
45°
13
69°
40°
14
59°
53°
15
70°
42°
16
74°
50°
17
70°
53°
18
62°
56°
19
61°
50°
20
64°
44°
21
61°
40°
22
64°
42°
23
66°
50°
24
63°
51°
25
69°
55°
26
68°
54°
27
69°
51°
28
69°
49°
29
68°
47°
30
69°
49°
1
68°
51°
2
65°
39°
3
63°
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 61° to 69°, with overnight lows between 39° and 55°. The average high for September is 66° with an average low of 48°. 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.
