S
M
T
W
T
F
S
30
94°
57°
31
91°
56°
1
90°
57°
2
91°
56°
3
90°
55°
4
89°
54°
5
88°
53°
6
88°
55°
7
89°
56°
8
88°
55°
9
88°
55°
10
89°
54°
11
88°
55°
12
88°
60°
13
89°
61°
14
93°
61°
15
93°
60°
16
92°
59°
17
89°
61°
18
90°
62°
19
93°
62°
20
94°
61°
21
92°
58°
22
90°
57°
23
89°
57°
24
90°
58°
25
90°
58°
26
91°
57°
27
Hist. Avg.
86°
57°
28
Hist. Avg.
85°
57°
29
Hist. Avg.
85°
56°
30
Hist. Avg.
85°
56°
1
Hist. Avg.
84°
56°
2
Hist. Avg.
84°
56°
3
Hist. Avg.
84°
55°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
*Temporarily Unavailable
September Weather in Thermalito
Thermalito's September 2026 forecast shows daily high temperatures ranging from 88° to 94°, with overnight lows between 53° and 62°. The average high for September is 90° with an average low of 58°. 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 Thermalito. See also: October | November | December.
