S
M
T
W
T
F
S
30
57°
48°
31
72°
46°
1
81°
40°
2
73°
49°
3
60°
41°
4
61°
39°
5
58°
40°
6
67°
45°
7
53°
49°
8
59°
49°
9
68°
42°
10
71°
48°
11
62°
39°
12
66°
43°
13
54°
47°
14
62°
46°
15
59°
42°
16
70°
42°
17
78°
43°
18
77°
49°
19
78°
49°
20
77°
51°
21
76°
50°
22
75°
51°
23
72°
50°
24
70°
49°
25
68°
47°
26
70°
41°
27
64°
44°
28
60°
34°
29
61°
40°
30
60°
39°
1
60°
35°
2
61°
36°
3
58°
34°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Eureka
Eureka's September 2026 forecast shows daily high temperatures ranging from 54° to 78°, with overnight lows between 34° and 51°. The average high for September is 67° with an average low of 44°. 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 Eureka. See also: October | November | December.
