S
M
T
W
T
F
S
30
84°
54°
31
76°
57°
1
76°
62°
2
80°
58°
3
81°
60°
4
82°
60°
5
83°
53°
6
80°
53°
7
75°
52°
8
74°
51°
9
74°
56°
10
78°
54°
11
77°
50°
12
72°
50°
13
74°
49°
14
73°
57°
15
76°
50°
16
78°
48°
17
71°
47°
18
69°
47°
19
69°
48°
20
70°
50°
21
69°
50°
22
69°
49°
23
71°
52°
24
72°
49°
25
74°
54°
26
75°
52°
27
75°
44°
28
69°
50°
29
67°
52°
30
74°
51°
1
67°
50°
2
70°
49°
3
65°
43°
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 65° to 84°, with overnight lows between 43° and 62°. The average high for September is 74° with an average low of 52°. 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.
