Friday Harbor — Water Temperature in April
Water Temperature Range
45°F
minimum
48°F
average
52°F
maximum
Water Temperature Chart for Month
The chart shows the average daily water temperature for each day of the month based on historical data.
Table of Water Temperatures by Day of the Month for Previous Years
| Day | 2025 | 2024 | 2023 | 2022 |
|---|---|---|---|---|
| APR 1 | 48°F | 48°F | 46°F | 46°F |
| APR 2 | 48°F | 48°F | 46°F | 46°F |
| APR 3 | 46°F | 48°F | 46°F | 46°F |
| APR 4 | 48°F | 48°F | 48°F | 46°F |
| APR 5 | 48°F | 46°F | 46°F | 46°F |
| APR 6 | 48°F | 46°F | 46°F | 46°F |
| APR 7 | 48°F | 46°F | 46°F | 46°F |
| APR 8 | 48°F | 48°F | 48°F | 46°F |
| APR 9 | 48°F | 48°F | 48°F | 46°F |
| APR 10 | 48°F | 48°F | 48°F | 48°F |
| APR 11 | 48°F | 48°F | 46°F | 48°F |
| APR 12 | 48°F | 48°F | 46°F | 48°F |
| APR 13 | 48°F | 48°F | 46°F | 48°F |
| APR 14 | 48°F | 48°F | 48°F | 48°F |
| APR 15 | 48°F | 48°F | 48°F | 48°F |
| APR 16 | 48°F | 48°F | 46°F | 48°F |
| APR 17 | 48°F | 48°F | 48°F | 48°F |
| APR 18 | 48°F | 48°F | 48°F | 48°F |
| APR 19 | 48°F | 48°F | 48°F | 50°F |
| APR 20 | 50°F | 48°F | 48°F | 50°F |
| APR 21 | 48°F | 50°F | 50°F | 50°F |
| APR 22 | 48°F | 48°F | 48°F | 50°F |
| APR 23 | 48°F | 50°F | 48°F | 50°F |
| APR 24 | 50°F | 48°F | 50°F | 50°F |
| APR 25 | 50°F | 48°F | 50°F | 50°F |
| APR 26 | 48°F | 48°F | 48°F | 50°F |
| APR 27 | 50°F | 50°F | 50°F | 50°F |
| APR 28 | 48°F | 48°F | 48°F | 50°F |
| APR 29 | 50°F | 48°F | 50°F | 50°F |
| APR 30 | 48°F | 48°F | 48°F | 50°F |
April: Climate and Swimming Opportunities
Average Night Air Temperature
41°F
Average Day Air Temperature
54°F
Precipitation Amount per Month
3.05 in
Number of Rainy Days
13
Daylight per Day
14 hrs
Sunshine per Day
5 hrs
Average Wind Speed
7 mph
Average Humidity
75%
At such water and air temperatures, swimming feels icy and can be a shock to the body. If you go in at all, keep it extremely short and warm up immediately afterward.