S
M
T
W
T
F
S
26
83°
69°
27
80°
70°
28
88°
71°
29
87°
70°
30
88°
70°
31
86°
71°
1
86°
70°
2
87°
71°
3
88°
70°
4
86°
69°
5
86°
70°
6
87°
71°
7
88°
69°
8
79°
65°
9
79°
66°
10
80°
67°
11
85°
70°
12
86°
70°
13
87°
71°
14
86°
69°
15
86°
68°
16
80°
67°
17
78°
65°
18
79°
68°
19
84°
67°
20
85°
66°
21
86°
67°
22
85°
63°
23
81°
59°
24
77°
59°
25
77°
60°
26
78°
59°
27
78°
58°
28
79°
58°
29
80°
62°
30
82°
65°
31
78°
65°
1
80°
64°
2
84°
61°
3
83°
55°
4
75°
56°
5
74°
64°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Prospect Heights
Prospect Heights's August 2026 forecast shows daily high temperatures ranging from 74° to 88°, with overnight lows between 55° and 71°. The average high for August is 83° with an average low of 66°. 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 Prospect Heights. See also: September | October | November.