S
M
T
W
T
F
S
30
102°
79°
31
101°
74°
1
100°
74°
2
101°
80°
3
99°
77°
4
100°
75°
5
101°
77°
6
103°
75°
7
103°
78°
8
104°
79°
9
103°
73°
10
91°
71°
11
99°
73°
12
100°
74°
13
95°
64°
14
90°
66°
15
89°
65°
16
96°
68°
17
92°
65°
18
92°
64°
19
84°
58°
20
79°
64°
21
89°
65°
22
89°
64°
23
88°
64°
24
86°
63°
25
77°
63°
26
80°
62°
27
82°
63°
28
85°
63°
29
80°
62°
30
83°
53°
1
72°
49°
2
73°
48°
3
71°
48°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Fairfax
Fairfax's September 2026 forecast shows daily high temperatures ranging from 71° to 104°, with overnight lows between 48° and 79°. The average high for September is 88° with an average low of 64°. 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 Fairfax. See also: October | November | December.
