S
M
T
W
T
F
S
30
86°
63°
31
78°
61°
1
68°
52°
2
68°
55°
3
62°
55°
4
70°
53°
5
75°
53°
6
78°
60°
7
85°
60°
8
91°
65°
9
99°
71°
10
95°
76°
11
88°
68°
12
84°
66°
13
78°
55°
14
86°
65°
15
83°
62°
16
75°
56°
17
72°
51°
18
83°
56°
19
89°
64°
20
72°
53°
21
73°
47°
22
72°
49°
23
73°
50°
24
73°
49°
25
70°
40°
26
67°
39°
27
68°
42°
28
67°
41°
29
65°
39°
30
64°
40°
1
66°
40°
2
65°
37°
3
64°
40°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Lassen Volcanic National Park
Lassen Volcanic National Park's September 2026 forecast shows daily high temperatures ranging from 64° to 73°, with overnight lows between 37° and 53°. The average high for September is 69° with an average low of 43°. 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 Lassen Volcanic National Park. See also: October | November | December.
