Port Jefferson — Water Temperature in July

Water Temperature Range

18°C

minimum

23°C

average

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

July: Climate and Swimming Opportunities

Average Night Air Temperature

18°C

Average Day Air Temperature

28°C

Precipitation Amount per Month

82 mm

Number of Rainy Days

Daylight per Day

15 hrs

Sunshine per Day

9 hrs

Average Wind Speed

13 km/h

Average Humidity

73%

At such water and air temperatures, swimming is pleasant and refreshing rather than hot. After you get in, it feels comfortable, and you’ll warm up quickly when you come out.