S
M
T
W
T
F
S
30
91°
81°
31
91°
78°
1
90°
78°
2
90°
79°
3
88°
80°
4
91°
79°
5
88°
77°
6
90°
76°
7
89°
76°
8
90°
78°
9
88°
76°
10
89°
77°
11
88°
77°
12
87°
78°
13
90°
75°
14
88°
76°
15
86°
78°
16
86°
78°
17
88°
77°
18
88°
78°
19
89°
78°
20
88°
77°
21
87°
78°
22
87°
77°
23
86°
76°
24
85°
75°
25
86°
78°
26
88°
77°
27
87°
78°
28
88°
78°
29
87°
77°
30
87°
77°
1
86°
76°
2
86°
77°
3
85°
76°
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 85° to 91°, with overnight lows between 75° and 80°. The average high for September is 88° 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.
