S
M
T
W
T
F
S
30
87°
57°
31
81°
56°
1
79°
60°
2
81°
61°
3
80°
56°
4
80°
55°
5
81°
58°
6
80°
60°
7
82°
56°
8
80°
54°
9
77°
60°
10
83°
53°
11
78°
52°
12
77°
52°
13
77°
55°
14
80°
57°
15
83°
58°
16
83°
58°
17
82°
57°
18
83°
56°
19
81°
48°
20
74°
48°
21
73°
52°
22
74°
54°
23
78°
54°
24
79°
55°
25
80°
49°
26
79°
45°
27
75°
47°
28
71°
45°
29
71°
44°
30
72°
51°
1
71°
44°
2
70°
43°
3
Hist. Avg.
73°
47°
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 87°, with overnight lows between 43° and 61°. The average high for September is 78° with an average low of 53°. 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.
