S
M
T
W
T
F
S
30
100°
80°
31
100°
81°
1
99°
81°
2
101°
82°
3
100°
80°
4
98°
79°
5
100°
79°
6
98°
78°
7
97°
79°
8
98°
78°
9
97°
79°
10
96°
79°
11
96°
77°
12
94°
78°
13
95°
79°
14
92°
75°
15
89°
77°
16
90°
76°
17
90°
74°
18
89°
75°
19
88°
75°
20
89°
76°
21
89°
76°
22
90°
75°
23
88°
76°
24
87°
75°
25
87°
75°
26
86°
74°
27
84°
75°
28
86°
75°
29
87°
73°
30
87°
73°
1
86°
75°
2
86°
74°
3
87°
74°
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 84° to 101°, with overnight lows between 73° and 82°. The average high for September is 92° with an average low of 77°. 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.
