S
M
T
W
T
F
S
30
90°
65°
31
94°
64°
1
96°
68°
2
97°
69°
3
96°
70°
4
96°
70°
5
95°
69°
6
84°
60°
7
83°
56°
8
91°
57°
9
80°
65°
10
75°
62°
11
82°
64°
12
90°
61°
13
81°
57°
14
77°
67°
15
90°
68°
16
85°
70°
17
85°
64°
18
80°
66°
19
82°
65°
20
68°
54°
21
69°
52°
22
70°
55°
23
73°
56°
24
74°
54°
25
75°
56°
26
73°
50°
27
77°
56°
28
75°
56°
29
72°
56°
30
74°
55°
1
73°
54°
2
75°
54°
3
72°
53°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Walnut
Walnut's September 2026 forecast shows daily high temperatures ranging from 68° to 90°, with overnight lows between 50° and 70°. The average high for September is 76° with an average low of 58°. 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 Walnut. See also: October | November | December.
