S
M
T
W
T
F
S
30
76°
58°
31
79°
61°
1
76°
61°
2
82°
53°
3
75°
51°
4
73°
52°
5
73°
51°
6
74°
56°
7
80°
59°
8
82°
61°
9
82°
55°
10
76°
53°
11
74°
59°
12
76°
55°
13
80°
50°
14
73°
50°
15
71°
48°
16
72°
50°
17
74°
56°
18
79°
46°
19
71°
53°
20
72°
47°
21
74°
53°
22
71°
55°
23
78°
56°
24
78°
55°
25
77°
55°
26
77°
54°
27
76°
54°
28
78°
53°
29
76°
53°
30
75°
54°
1
77°
49°
2
77°
44°
3
74°
42°
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 71° to 82°, with overnight lows between 42° and 61°. The average high for September is 76° with an average low of 53°. 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.
