S
M
T
W
T
F
S
30
81°
67°
31
91°
70°
1
93°
74°
2
94°
74°
3
93°
75°
4
92°
74°
5
86°
72°
6
81°
64°
7
82°
63°
8
85°
62°
9
80°
67°
10
77°
61°
11
82°
58°
12
85°
61°
13
75°
53°
14
71°
66°
15
86°
68°
16
77°
67°
17
76°
60°
18
73°
60°
19
74°
56°
20
70°
54°
21
71°
52°
22
72°
55°
23
72°
53°
24
73°
55°
25
81°
55°
26
78°
57°
27
78°
58°
28
76°
58°
29
74°
58°
30
74°
57°
1
75°
56°
2
75°
55°
3
73°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Romeoville
Romeoville's September 2026 forecast shows daily high temperatures ranging from 70° to 86°, with overnight lows between 52° and 68°. The average high for September is 75° with an average low of 58°. 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 Romeoville. See also: October | November | December.
