S
M
T
W
T
F
S
30
78°
69°
31
91°
73°
1
95°
72°
2
96°
72°
3
95°
72°
4
95°
68°
5
91°
66°
6
85°
60°
7
83°
63°
8
89°
68°
9
86°
65°
10
83°
61°
11
82°
60°
12
83°
62°
13
82°
60°
14
81°
57°
15
82°
57°
16
76°
53°
17
80°
59°
18
73°
55°
19
74°
58°
20
78°
57°
21
76°
58°
22
77°
56°
23
74°
55°
24
76°
55°
25
77°
54°
26
75°
49°
27
66°
45°
28
64°
43°
29
65°
45°
30
65°
42°
1
64°
48°
2
66°
50°
3
65°
48°
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 64° to 95°, with overnight lows between 42° and 72°. The average high for September is 78° with an average low of 56°. 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.
