S
M
T
W
T
F
S
30
100°
67°
31
100°
67°
1
99°
66°
2
100°
66°
3
100°
68°
4
98°
66°
5
99°
63°
6
99°
58°
7
93°
56°
8
91°
58°
9
92°
60°
10
95°
63°
11
98°
62°
12
98°
62°
13
96°
65°
14
98°
64°
15
98°
59°
16
96°
60°
17
95°
62°
18
96°
64°
19
95°
62°
20
95°
58°
21
93°
62°
22
88°
61°
23
85°
58°
24
86°
62°
25
87°
60°
26
90°
57°
27
86°
58°
28
86°
61°
29
85°
55°
30
84°
60°
1
84°
63°
2
90°
61°
3
83°
60°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Grand Terrace
Grand Terrace's September 2026 forecast shows daily high temperatures ranging from 83° to 100°, with overnight lows between 55° and 68°. The average high for September is 93° with an average low of 62°. 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 Grand Terrace. See also: October | November | December.
