Stony Brook — Water Temperature, Sea Conditions & Trends
This page provides clear and up-to-date information about water temperature for Stony Brook (New York, United States). It includes the current water temperature, daily data for the last month presented in a simple chart, and a 7-day forecast. The page also compares today’s value with typical averages for this period, shows usual monthly ranges during the year, and lists nearby beaches with short descriptions. Local weather for the next few days and general details about Stony Brook help you plan your visit and choose the best time for swimming.
Current Water Temperature
Water temperature in Stony Brook in the Atlantic Ocean today is 18°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming.
It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Water Temperature Chart Over the Last 30 Days
Water temperature in Stony Brook has risen over the last week and month. Currently, the sea water at this location is slightly warmer than average for this day in previous years.
According to our forecast, Water temperature in Stony Brook will be 17.8°C in the next 7 days. See the table below for daily data for the upcoming week.
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| JUN 5 | 14.4°C | 15.8°C | |
| JUN 6 | 14.9°C | 16.0°C | |
| JUN 7 | 16.3°C | 16.3°C | |
| JUN 8 | 16.4°C | 15.8°C | |
| JUN 9 | 16.4°C | 16.8°C | |
| JUN 10 | 16.9°C | 17.0°C | |
| JUN 11 | 17.2°C | 17.0°C | |
| JUN 12 | 17.4°C | 17.3°C | |
| JUN 13 | 18.4°C | 17.3°C | 18.4°C |
| JUN 14 | 17.0°C | 18.3°C | |
| JUN 15 | 17.3°C | 18.2°C | |
| JUN 16 | 17.5°C | 18.2°C | |
| JUN 17 | 17.0°C | 18.1°C | |
| JUN 18 | 17.5°C | 18.0°C | |
| JUN 19 | 17.5°C | 17.9°C | |
| JUN 20 | 18.5°C | 17.8°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Water temperature data for this location is gathered from various sources, including buoys and satellite sea and ocean surface maps provided by the NOAA agency. We also incorporate data from local authorities in each specific location worldwide to ensure more accurate temperature readings.
Annual Water Temperature Overview by Month
Monthly Water Temp Ranges
Annual Water Temperature Trend
Stony Brook, on the north shore of Long Island, sits beside a small harbor opening into Long Island Sound. The water here is coastal and tidally influenced, so temperatures vary with the seasons and with how shallow or sheltered a spot is. Typical sea surface temperatures range from around 0–6 °C in the coldest months of winter, rising through spring to roughly 5–12 °C. By late spring and early summer the water warms more noticeably, and peak summer temperatures commonly reach about 18–25 °C in July and August in the harbor and nearby shallow areas, with isolated warm spells occasionally pushing a degree or two higher. In autumn the Sound cools again, generally settling in the range of about 10–18 °C as the season progresses.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 2°C | 6°C | 10°C |
| February | 2°C | 4°C | 7°C |
| March | 2°C | 5°C | 7°C |
| April | 4°C | 8°C | 12°C |
| May | 8°C | 12°C | 17°C |
| June | 13°C | 17°C | 23°C |
| July | 18°C | 23°C | 26°C |
| August | 21°C | 24°C | 26°C |
| September | 18°C | 22°C | 25°C |
| October | 13°C | 19°C | 23°C |
| November | 9°C | 14°C | 18°C |
| December | 5°C | 9°C | 13°C |
* Click on a month to view detailed water temperature data.
Stony Brook: Weather Forecast
June 14
June 15
June 16
June 17
June 18
Location, Beaches & Local Information
Nearby Beaches & Facilities
Stony Brook Beach
Stony Brook Yacht Club
Old Field Club
West Meadow Beach
Schubert Beach
Long Beach Town Park
Brookhaven Town Beach
Flax Pond Beach
Bayview Beach
Swimming Conditions
Swimming and beach holidays in and around Stony Brook are largely seasonal, with the most comfortable conditions for casual swimmers and families occurring in midsummer when water temperatures are warmest. Public and community beaches, as well as sheltered spots in the harbor, offer opportunities for bathing, paddle sports and shoreline recreation, though water can remain brisk early and late in the season. Visitors should plan swims for the warmest part of summer if they prefer water above 20 °C, and be prepared for cooler, choppier conditions in shoulder months. Facilities and services tend to operate on a summer schedule, and those seeking a full beach holiday will find a mix of sandy stretches, calm inlet areas and nearby access to boat launches and kayaking for exploring the Sound.