S
M
T
W
T
F
S
26
94°
66°
27
92°
64°
28
87°
66°
29
88°
69°
30
93°
68°
31
89°
69°
1
94°
69°
2
94°
68°
3
93°
69°
4
91°
69°
5
93°
68°
6
94°
70°
7
94°
70°
8
95°
68°
9
89°
62°
10
82°
61°
11
83°
67°
12
91°
68°
13
91°
64°
14
83°
59°
15
82°
60°
16
84°
66°
17
91°
65°
18
85°
62°
19
87°
66°
20
89°
66°
21
83°
65°
22
86°
64°
23
82°
65°
24
90°
61°
25
90°
64°
26
89°
54°
27
88°
52°
28
80°
52°
29
79°
53°
30
80°
57°
31
80°
53°
1
82°
50°
2
80°
49°
3
76°
50°
4
77°
51°
5
79°
58°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Grinnell
Grinnell's August 2026 forecast shows daily high temperatures ranging from 76° to 95°, with overnight lows between 49° and 70°. The average high for August is 87° with an average low of 62°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how August weather will actually feel in Grinnell. See also: September | October | November.
