S
M
T
W
T
F
S
30
91°
65°
31
81°
66°
1
90°
67°
2
90°
66°
3
89°
68°
4
91°
64°
5
90°
59°
6
81°
55°
7
81°
56°
8
82°
64°
9
83°
59°
10
82°
55°
11
77°
53°
12
75°
57°
13
78°
61°
14
77°
52°
15
85°
51°
16
78°
50°
17
74°
50°
18
73°
51°
19
74°
50°
20
72°
49°
21
73°
49°
22
74°
50°
23
74°
50°
24
76°
53°
25
78°
56°
26
80°
52°
27
81°
57°
28
74°
50°
29
80°
47°
30
79°
51°
1
74°
50°
2
71°
46°
3
70°
54°
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 70° to 91°, with overnight lows between 46° and 68°. The average high for September is 79° 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.
