S
M
T
W
T
F
S
30
91°
72°
31
91°
72°
1
92°
71°
2
92°
72°
3
91°
71°
4
91°
72°
5
90°
71°
6
91°
71°
7
92°
70°
8
92°
71°
9
91°
71°
10
92°
70°
11
92°
71°
12
91°
70°
13
91°
71°
14
89°
66°
15
82°
67°
16
88°
67°
17
89°
65°
18
90°
58°
19
80°
57°
20
79°
57°
21
83°
59°
22
86°
59°
23
87°
63°
24
86°
61°
25
82°
63°
26
86°
62°
27
84°
62°
28
85°
61°
29
77°
54°
30
76°
54°
1
81°
59°
2
84°
58°
3
84°
59°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Brownsville
Brownsville's September 2026 forecast shows daily high temperatures ranging from 76° to 92°, with overnight lows between 54° and 72°. The average high for September is 87° with an average low of 65°. 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 Brownsville. See also: October | November | December.
