S
M
T
W
T
F
S
30
82°
57°
31
77°
63°
1
77°
57°
2
77°
55°
3
79°
59°
4
88°
64°
5
70°
59°
6
75°
55°
7
82°
61°
8
89°
61°
9
68°
51°
10
65°
50°
11
66°
51°
12
66°
52°
13
69°
53°
14
70°
54°
15
73°
56°
16
64°
51°
17
63°
49°
18
62°
50°
19
63°
46°
20
65°
45°
21
68°
48°
22
66°
44°
23
70°
46°
24
70°
45°
25
69°
48°
26
70°
46°
27
65°
41°
28
65°
40°
29
66°
39°
30
67°
46°
1
61°
40°
2
60°
39°
3
65°
40°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in Grassau
Grassau's September 2026 forecast shows daily high temperatures ranging from 60° to 89°, with overnight lows between 39° and 61°. The average high for September is 68° with an average low of 48°. 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 Grassau. See also: October | November | December.
