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
80°
54°
14
78°
67°
15
90°
69°
16
85°
70°
17
85°
64°
18
84°
66°
19
86°
65°
20
81°
63°
21
74°
60°
22
70°
57°
23
71°
56°
24
71°
57°
25
72°
56°
26
73°
55°
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 70° to 90°, with overnight lows between 53° and 70°. The average high for September is 77° 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 Walnut. See also: October | November | December.
