S
M
T
W
T
F
S
30
89°
59°
31
90°
60°
1
90°
61°
2
91°
60°
3
89°
58°
4
89°
58°
5
90°
59°
6
91°
62°
7
93°
57°
8
91°
56°
9
91°
56°
10
90°
55°
11
89°
56°
12
90°
57°
13
89°
59°
14
90°
62°
15
91°
59°
16
90°
63°
17
93°
62°
18
96°
63°
19
95°
64°
20
97°
64°
21
97°
61°
22
94°
59°
23
90°
58°
24
91°
55°
25
87°
58°
26
90°
58°
27
92°
57°
28
92°
58°
29
91°
55°
30
92°
59°
1
90°
60°
2
91°
59°
3
90°
58°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Three Rivers
Three Rivers's September 2026 forecast shows daily high temperatures ranging from 87° to 97°, with overnight lows between 55° and 64°. The average high for September is 91° with an average low of 59°. 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 Three Rivers. See also: October | November | December.