Onset water temp

This data the coastal Onset ocean water temperature today, tomorrow and the upcoming days. Besides, you can also get information about the weather and surf forecast, as well as the data on sunrise / sunset and moonrise / moonset at a given point on any given day.

Current ocean temperature in Onset

Water temperature in Onset today is 69.6°F. Based on our historical data over a period of ten years, the warmest water in this day in the Atlantic Ocean near Onset was recorded in 2018 and was 75.4°F, and the coldest was recorded in 2007 at 66.2°F. Sea water temperature in Onset is expected to drop to 69.3°F in the next 10 days. September average water temperature in Onset is 68.5°F, the minimum temperature is 63.1°F, and the maximum is 77°F.

The swimming season in Onset lasts from July to September. During those months, Onset water temperature does not drop below 68°F and therefore suitable for comfortable swimming. The average water temperature in Onset in winter reaches 39.9°F, in spring 46.2°F, in summer the average temperature rises to 69.1°F, and in autumn it is 61°F.

Onset water temperature now

The ocean salinity in Onset is 28.85‰, and the average salinity of the World Ocean is 35‰.

Surf Forecast in Onset for today

Another important indicators for a comfortable holiday on the beach are the presence and height of the waves, as well as the speed and direction of the wind. Please find below data on the swell size for Onset. We calculate the swell size based on the mean wave height (trough to crest) of each third highest wave. For more information on surf forecasts for the next ten days, please visit sea state forecast Onset. Data in table shown for September 5, 2025, time in GMT 0 format (you can change the time zone on the sea state forecast page)

Surf report in Onset

Onset weather forecast

Current temperature and weather

Data in a table show Onset temperature today (September 5, 2025). For more information and forecast for a few days, go to the weather forecast Onset.

0-3 h	3-6 h	6-9 h	9-12 h
64°F	65.3°F	67.5°F	69.8°F

12-15 h	15-18 h	18-21 h	21-24 h
74.3°F	73.6°F	71.1°F	69.4°F

Onset water temperature by month

These figures shows the average, minimum and maximum monthly sea temperature in Onset. In addition to the table values, the graph below displays of changes average surface temperature during the year. Values are calculated based on the data over the past 10 years. Using them, you can check the water temperature in Onset on any day of this period that interests you. Click on the month link and you will see a table for each day, or alternatively you can view the temperature curve of the month and select 2 different years you want to compare, either in a table or as a curve

Chart monthly average water temperature in Onset

The nearest beaches and cities from Onset with the water temperature today, as well as the air temperature and the state of the weather during the day and the average wave height for today

	Water	Weather		Wave
Weweantic	70.2°F	73.4°F		2' 1"
Monument Beach	71.2°F	71.6°F		1' 11"
Pocasset	71.2°F	71.6°F		1' 11"
Old Silver Beach	71.2°F	71.6°F		1' 11"
Wareham	71.2°F	71.6°F		1' 11"
Bourne	71.2°F	71.6°F		1' 11"
North Falmouth	71.2°F	71.6°F		1' 11"
Little Harbor Beach	71.2°F	71.6°F		1' 11"
Buzzards Bay	71.1°F	71.6°F		1' 11"
East Wareham	71.1°F	71.6°F		1' 11"

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Onset Beach

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Our report for Onset is compiled using satellite data together with in-situ observations to get the most reliable daily data of sea surface temperatures, surf forecasts, current temperatures and weather forecasts.