Stony Brook — Water Temperature in December

Water Temperature Range

5°C

minimum

9°C

average

13°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	2025	2024	2023	2022
DEC 1	11°C	10°C	12°C	10°C
DEC 2	11°C	10°C	12°C	9°C
DEC 3	10°C	10°C	11°C	9°C
DEC 4	10°C	10°C	11°C	9°C
DEC 5	11°C	10°C	11°C	10°C
DEC 6	10°C	9°C	11°C	10°C
DEC 7	10°C	9°C	10°C	10°C
DEC 8	10°C	9°C	10°C	10°C
DEC 9	10°C	9°C	10°C	10°C
DEC 10	9°C	8°C	10°C	10°C
DEC 11	9°C	8°C	9°C	9°C
DEC 12	9°C	8°C	9°C	9°C
DEC 13	9°C	8°C	10°C	9°C
DEC 14	9°C	8°C	10°C	9°C
DEC 15	9°C	8°C	10°C	9°C
DEC 16	9°C	8°C	9°C	9°C
DEC 17	8°C	7°C	8°C	7°C
DEC 18	8°C	7°C	9°C	8°C
DEC 19	8°C	6°C	10°C	8°C
DEC 20	8°C	6°C	9°C	9°C
DEC 21	8°C	7°C	10°C	8°C
DEC 22	9°C	7°C	9°C	8°C
DEC 23	8°C	7°C	9°C	8°C
DEC 24	8°C	7°C	9°C	8°C
DEC 25	8°C	7°C	9°C	7°C
DEC 26	8°C	7°C	8°C	7°C
DEC 27	7°C	6°C	8°C	7°C
DEC 28	8°C	7°C	9°C	7°C
DEC 29	7°C	6°C	7°C	7°C
DEC 30	6°C	5°C	7°C	7°C
DEC 31	7°C	5°C	7°C	8°C

December: Climate and Swimming Opportunities

Average Night Air Temperature

-2°C

Average Day Air Temperature

7°C

Precipitation Amount per Month

112 mm

Number of Rainy Days

Daylight per Day

9 hrs

Sunshine per Day

5 hrs

Average Wind Speed

19 km/h

Average Humidity

68%

At such water and air temperatures, swimming is extremely harsh and generally not enjoyable. The risk of rapid chilling is high, so most people avoid entering the water.