S
M
T
W
T
F
S
30
83°
55°
31
67°
56°
1
73°
59°
2
72°
56°
3
74°
55°
4
76°
52°
5
78°
48°
6
79°
54°
7
89°
49°
8
95°
51°
9
97°
59°
10
101°
68°
11
86°
59°
12
77°
58°
13
79°
50°
14
88°
55°
15
83°
57°
16
77°
57°
17
80°
56°
18
84°
56°
19
86°
57°
20
82°
57°
21
84°
56°
22
83°
59°
23
84°
58°
24
85°
57°
25
89°
58°
26
91°
60°
27
79°
57°
28
78°
53°
29
78°
55°
30
80°
55°
1
84°
56°
2
79°
55°
3
79°
54°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Walnut Creek
Walnut Creek's September 2026 forecast shows daily high temperatures ranging from 77° to 91°, with overnight lows between 53° and 60°. The average high for September is 83° 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 Creek. See also: October | November | December.
