San Mateo — Water Temperature in April

Water Temperature Range

9°C

minimum

13°C

average

16°C

maximum

Get instant access to real-time water temperatures for this and all other locations with our iOS and Android apps.

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	2026	2025	2024	2023
APR 1	-10°C	16°C	12°C	13°C
APR 2	16°C	13°C	12°C	14°C
APR 3	16°C	13°C	12°C	14°C
APR 4	16°C	12°C	13°C	14°C
APR 5	16°C	13°C	12°C	14°C
APR 6	16°C	12°C	12°C	13°C
APR 7	16°C	13°C	12°C	14°C
APR 8	17°C	13°C	13°C	13°C
APR 9	16°C	12°C	13°C	13°C
APR 10	16°C	13°C	13°C	13°C
APR 11	17°C	13°C	13°C	14°C
APR 12	17°C	13°C	13°C	15°C
APR 13	16°C	13°C	13°C	15°C
APR 14	16°C	13°C	13°C	15°C
APR 15	16°C	12°C	13°C	15°C
APR 16	17°C	13°C	12°C	15°C
APR 17	16°C	12°C	12°C	15°C
APR 18	17°C	13°C	13°C	14°C
APR 19	16°C	12°C	13°C	15°C
APR 20	17°C	14°C	13°C	15°C
APR 21	16°C	13°C	13°C	15°C
APR 22	16°C	13°C	13°C	14°C
APR 23	16°C	12°C	12°C	14°C
APR 24	15°C	13°C	13°C	15°C
APR 25	16°C	13°C	14°C	15°C
APR 26	16°C	13°C	12°C	15°C
APR 27	16°C	13°C	12°C	15°C
APR 28	16°C	12°C	12°C	14°C
APR 29	16°C	13°C	12°C	15°C
APR 30	16°C	12°C	12°C	15°C

April: Climate and Swimming Opportunities

Average Night Air Temperature

10°C

Average Day Air Temperature

19°C

Precipitation Amount per Month

50 mm

Number of Rainy Days

Daylight per Day

13 hrs

Sunshine per Day

10 hrs

Average Wind Speed

16 km/h

Average Humidity

70%

With such a ratio between the average monthly temperatures of water and air, swimming feels very cold and is only for cold-water enthusiasts. Most people will prefer just a brief splash, because warming up afterward can take time.