S
M
T
W
T
F
S
26
68°
49°
27
72°
48°
28
67°
44°
29
70°
48°
30
67°
45°
1
67°
51°
2
68°
55°
3
78°
52°
4
68°
46°
5
67°
45°
6
68°
46°
7
73°
53°
8
74°
50°
9
70°
48°
10
69°
47°
11
69°
48°
12
74°
59°
13
81°
60°
14
80°
59°
15
79°
53°
16
71°
50°
17
72°
57°
18
81°
61°
19
83°
61°
20
76°
57°
21
74°
52°
22
76°
57°
23
77°
54°
24
76°
58°
25
79°
58°
26
82°
61°
27
83°
61°
28
84°
62°
29
87°
60°
30
85°
59°
31
84°
55°
1
82°
55°
2
78°
56°
3
79°
54°
4
79°
57°
5
80°
57°
6
79°
65°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
May Weather in Hillsboro
Hillsboro's May 2026 forecast shows daily high temperatures ranging from 67° to 87°, with overnight lows between 44° and 65°. The average high for May is 76° with an average low of 54°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how May weather will actually feel in Hillsboro. See also: June | July | August.