S
M
T
W
T
F
S
30
89°
66°
31
89°
67°
1
96°
71°
2
92°
71°
3
97°
69°
4
94°
71°
5
85°
65°
6
81°
61°
7
81°
60°
8
85°
65°
9
91°
69°
10
92°
65°
11
85°
61°
12
85°
66°
13
83°
64°
14
84°
62°
15
80°
59°
16
74°
63°
17
74°
58°
18
73°
55°
19
75°
56°
20
80°
60°
21
77°
61°
22
78°
62°
23
76°
60°
24
76°
58°
25
75°
60°
26
78°
60°
27
78°
59°
28
74°
54°
29
68°
51°
30
71°
55°
1
70°
56°
2
70°
54°
3
66°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Manassas
Manassas's September 2026 forecast shows daily high temperatures ranging from 66° to 97°, with overnight lows between 51° and 71°. The average high for September is 80° with an average low of 61°. 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 Manassas. See also: October | November | December.
