S
M
T
W
T
F
S
30
85°
47°
31
83°
41°
1
75°
40°
2
71°
41°
3
72°
44°
4
82°
43°
5
83°
48°
6
82°
44°
7
73°
41°
8
69°
37°
9
68°
39°
10
71°
37°
11
69°
41°
12
71°
44°
13
75°
45°
14
80°
48°
15
81°
48°
16
80°
49°
17
79°
48°
18
72°
47°
19
71°
47°
20
76°
46°
21
76°
46°
22
77°
45°
23
75°
46°
24
73°
42°
25
71°
34°
26
63°
38°
27
63°
42°
28
69°
31°
29
61°
31°
30
61°
35°
1
63°
40°
2
71°
42°
3
72°
42°
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 85°, with overnight lows between 31° and 49°. The average high for September is 73° with an average low of 42°. 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.
