Dennis Port — Water Temperature, Sea Conditions & Trends
This page provides clear and up-to-date information about water temperature for Dennis Port (Massachusetts, 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 Dennis Port help you plan your visit and choose the best time for swimming.
Current Water Temperature
Water temperature in Dennis Port in the Atlantic Ocean today is 20°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 68°F (20°C) to 74°F (23°C). The water is warm and pleasant for swimming, and in this range, one can stay in the water for extended periods without the risk of hypothermia. This is the ideal temperature for relaxation, swimming, and water sports. Families with children, as well as outdoor enthusiasts, will enjoy swimming and time spent in the water. For most people, this is the optimal temperature for a comfortable beach experience.
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 Dennis Port has risen over the last week and month. Currently, the sea water temperature at this location matches the average for this day in previous years.
According to our forecast, Water temperature in Dennis Port will be 15.3°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 22 | 18.6°C | 18.3°C | |
| JUN 23 | 18.1°C | 18.8°C | |
| JUN 24 | 18.3°C | 19.0°C | |
| JUN 25 | 19.0°C | 19.0°C | |
| JUN 26 | 18.7°C | 19.3°C | |
| JUN 27 | 19.0°C | 20.0°C | |
| JUN 28 | 19.6°C | 19.8°C | |
| JUN 29 | 19.6°C | 20.0°C | |
| JUN 30 | 19.7°C | 20.0°C | 19.7°C |
| JUL 1 | 22.0°C | 19.1°C | |
| JUL 2 | 22.0°C | 18.4°C | |
| JUL 3 | 21.3°C | 17.8°C | |
| JUL 4 | 21.0°C | 17.2°C | |
| JUL 5 | 19.3°C | 16.6°C | |
| JUL 6 | 13.3°C | 15.9°C | |
| JUL 7 | 12.3°C | 15.3°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
Dennis Port sits on the southern side of Cape Cod, fronting the relatively shallow waters of Nantucket Sound, which tend to warm earlier and stay milder than the open Atlantic. Seasonal surface temperatures typically run near freezing in the coldest months, about 0–4 °C in winter. Spring sees a steady rise, with waters averaging roughly 4–12 °C from March through May. By early summer temperatures commonly reach 12–18 °C in June and peak in July and August, when typical values are around 17–22 °C and can occasionally climb to the low 20s °C during warm spells. In autumn the sound cools gradually, with September and October often ranging from 12–19 °C and dropping back toward single digits by late fall.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 2°C | 5°C | 8°C |
| February | 2°C | 3°C | 6°C |
| March | 2°C | 4°C | 7°C |
| April | 4°C | 7°C | 10°C |
| May | 6°C | 11°C | 16°C |
| June | 10°C | 16°C | 22°C |
| July | 15°C | 21°C | 24°C |
| August | 18°C | 22°C | 25°C |
| September | 16°C | 19°C | 23°C |
| October | 9°C | 16°C | 20°C |
| November | 7°C | 11°C | 15°C |
| December | 4°C | 7°C | 11°C |
* Click on a month to view detailed water temperature data.
Dennis Port: Weather Forecast
July 1
July 2
July 3
July 4
Location, Beaches & Local Information
Nearby Beaches & Facilities
Raycroft Beach
Raycroft
Inman Road Beach
Glendon Road
Glendon Road Beach
Sea Street Beach
Clipper Lane
Haigis
Haigis Beach
Swimming Conditions
Swimming around Dennis Port benefits from the sheltered, shallow character of Nantucket Sound, making it popular for family beach days and watersports when temperatures are comfortable. The warmer summer waters make for pleasant bathing, wading, and snorkeling close to shore, while calmer conditions favor paddleboarding and beginner-friendly swimming; lifeguarded hours and seasonal facilities are usually available at main beach access points. Outside of midsummer, swimmers frequently use wetsuits for comfort and longer exposure, and it’s sensible to check local beach advisories for water quality or safety notices before entering. Wind, tides and occasional currents can affect conditions, so choosing protected coves and observing posted guidance helps ensure a safe and enjoyable beach holiday.