S
M
T
W
T
F
S
30
94°
56°
31
92°
55°
1
92°
56°
2
92°
58°
3
93°
57°
4
93°
54°
5
91°
52°
6
88°
51°
7
85°
55°
8
86°
55°
9
90°
56°
10
90°
56°
11
91°
54°
12
86°
54°
13
89°
52°
14
89°
53°
15
85°
50°
16
83°
49°
17
86°
51°
18
89°
53°
19
89°
54°
20
88°
52°
21
88°
53°
22
82°
51°
23
80°
48°
24
82°
51°
25
81°
47°
26
81°
46°
27
80°
45°
28
78°
44°
29
79°
45°
30
78°
46°
1
78°
53°
2
83°
52°
3
85°
51°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Upper Lake
Upper Lake's September 2026 forecast shows daily high temperatures ranging from 78° to 94°, with overnight lows between 44° and 58°. The average high for September is 86° 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 Upper Lake. See also: October | November | December.
