S
M
T
W
T
F
S
29
44°
32°
30
49°
31°
31
54°
37°
1
49°
41°
2
58°
42°
3
54°
43°
4
59°
41°
5
62°
44°
6
62°
40°
7
55°
35°
8
58°
36°
9
61°
36°
10
60°
39°
11
51°
43°
12
55°
45°
13
57°
45°
14
49°
39°
15
43°
33°
16
52°
33°
17
57°
41°
18
63°
46°
19
66°
49°
20
67°
48°
21
59°
48°
22
60°
44°
23
61°
43°
24
62°
45°
25
63°
46°
26
62°
46°
27
61°
45°
28
64°
45°
29
64°
46°
30
60°
42°
1
54°
39°
2
54°
40°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
April Weather in San Juan Island
San Juan Island's April 2026 forecast shows daily high temperatures ranging from 54° to 67°, with overnight lows between 39° and 49°. The average high for April is 61° with an average low of 45°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how April weather will actually feel in San Juan Island. See also: May | June | July.
