San Mateo — Water Temperature in July

Water Temperature Range

11°C

minimum

14°C

average

18°C

maximum

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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
JUL 1	-	17°C	12°C	16°C
JUL 2	17°C	14°C	12°C	16°C
JUL 3	18°C	13°C	12°C	16°C
JUL 4	17°C	13°C	12°C	17°C
JUL 5	17°C	14°C	13°C	17°C
JUL 6	18°C	14°C	12°C	17°C
JUL 7	18°C	14°C	13°C	17°C
JUL 8	18°C	14°C	13°C	16°C
JUL 9	18°C	14°C	13°C	17°C
JUL 10	17°C	14°C	13°C	17°C
JUL 11	17°C	14°C	13°C	16°C
JUL 12	18°C	14°C	13°C	16°C
JUL 13	17°C	14°C	14°C	15°C
JUL 14	17°C	14°C	13°C	15°C
JUL 15	17°C	14°C	14°C	16°C
JUL 16	18°C	14°C	14°C	16°C
JUL 17	18°C	14°C	14°C	16°C
JUL 18	18°C	14°C	13°C	16°C
JUL 19	18°C	14°C	14°C	17°C
JUL 20	18°C	14°C	14°C	16°C
JUL 21	17°C	14°C	14°C	16°C
JUL 22	18°C	14°C	14°C	16°C
JUL 23	18°C	13°C	14°C	16°C
JUL 24	18°C	14°C	14°C	16°C
JUL 25	18°C	14°C	15°C	16°C
JUL 26	18°C	14°C	14°C	16°C
JUL 27	-	15°C	14°C	17°C
JUL 28	-	14°C	14°C	16°C
JUL 29	-	15°C	15°C	17°C
JUL 30	-	15°C	14°C	17°C
JUL 31	-	15°C	15°C	16°C

July: Climate and Swimming Opportunities

Average Night Air Temperature

14°C

Average Day Air Temperature

21°C

Precipitation Amount per Month

1 mm

Number of Rainy Days

Daylight per Day

14 hrs

Sunshine per Day

10 hrs

Average Wind Speed

15 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.