Portsea – current water temperature and swimming conditions

This page shows the current water temperature at Portsea in Victoria. You can view recent sea temperature trends on a 30-day chart, check typical monthly water temperature ranges, and compare today’s reading with historical averages for this date. The page also includes a 7-day water temperature forecast, nearby beaches with similar conditions, local weather information, and a summary of swimming conditions to help you assess how suitable the water is for swimming.

Current Sea Water Temperature

18.8°C

Today

18.9°C

Yesterday

19.3°C

A Week Ago

The average sea water temperature today in Portsea is about 19°C.

Water Temperature in Portsea: Daily Trends, Historical Records, and Forecast

⚠️ Water in this range feels cool but still manageable for many swimmers. Short to moderate swims are comfortable, especially in warm weather. Some people may prefer a wetsuit for longer stays, particularly when swimming actively or outside peak summer conditions.

It’s important to note that these swimming tips and recommendations apply only in settled weather. When air temperatures drop below 20°C — and sometimes even below 25°C — swimming can feel uncomfortable, even when water temperatures are relatively high.

Water Temperature Over the Last 30 Days

From February 18 to March 20

Water temperatures in Portsea have been gradually cooling over the past month, with a further drop recorded during the last week.

According to our forecast, Sea water temperature in Portsea will be 19.0°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
Mar 12	19.1°C	19.3°C
Mar 13	19.2°C	19.3°C
Mar 14	19.3°C	18.5°C
Mar 15	19.1°C	18.8°C
Mar 16	18.8°C	19.3°C
Mar 17	18.7°C	19.0°C
Mar 18	18.7°C	18.8°C
Mar 19	18.9°C	18.8°C
Mar 20	18.8°C	18.8°C	18.8°C
Mar 21		19.0°C	18.8°C
Mar 22		19.0°C	18.9°C
Mar 23		18.8°C	18.9°C
Mar 24		18.5°C	18.9°C
Mar 25		19.0°C	19.0°C
Mar 26		19.0°C	19.0°C
Mar 27		18.5°C	19.0°C

* Current - Actual water temperature value

** Average - Average water temperature on this day in recent years

*** Forecast - Our water temperature forecast

Actual near-shore water temperatures in Portsea can vary by several degrees from the values shown, particularly after heavy rain, strong southerlies, or prolonged windy conditions. Certain wind patterns can trigger upwelling, where cooler, deeper water is pushed to the surface and replaces the warmer top layer, leading to noticeable short-term changes in water temperature.

Our water temperature forecast is produced using a proprietary mathematical model that combines real-time measurements with long-term historical patterns, local weather conditions, wind strength and direction, and air temperature specific to each coastal region. To improve accuracy, we cross-check data from nearby locations and use multiple sources, including offshore buoys, satellite-based sea surface maps, and observations provided by local authorities.

Annual Water Temperature Overview by Month

Monthly Water Temp Ranges

30°C

25°C

20°C

15°C

10°c

5°C

0°C

Annual Water Temperature Trend

Portsea sits at the very tip of the Mornington Peninsula, where Port Phillip Bay narrows toward the Bass Strait, and this location shapes both water temperature and swimming conditions. In summer, water temperatures usually range from about 18–22 °C, feeling refreshing but comfortable on warm days. Autumn often stays mild, with temperatures commonly around 16–20 °C, while spring is cooler at roughly 14–18 °C as the water slowly warms after winter. During winter, temperatures typically drop to around 11–14 °C, which feels cold and generally limits swimming to short dips or those wearing wetsuits.

Monthly Water Temperature Range (Min, Max & Average)

Month	Min	Avg	Max
January	15°C	19°C	22°C
February	17°C	19°C	22°C
March	17°C	19°C	21°C
April	15°C	17°C	20°C
May	14°C	16°C	18°C
June	12°C	14°C	16°C
July	10°C	13°C	15°C
August	10°C	13°C	14°C
September	11°C	13°C	15°C
October	11°C	14°C	16°C
November	13°C	16°C	18°C
December	15°C	17°C	21°C

* Click on a month to view detailed water temperature data.

Portsea: Weather Forecast

March 21

15°C / 18°C

clear sky

humidity: 77% | wind: 14 kmh

March 22

17°C / 19°C

broken clouds: 51-84%

humidity: 71% | wind: 7 kmh

March 23

17°C / 19°C

clear sky

humidity: 69% | wind: 11 kmh

March 24

18°C / 19°C

broken clouds: 51-84%

humidity: 79% | wind: 7 kmh

Local Water Conditions and Nearby Spots

Nearby Beaches and Water Temperatures

Weroona Bay

⭐ 4.6/5

18.4°C

Shelly Beach

⭐ 3.6/5

19.2°C

Cadet Beach

⭐ 3.5/5

19.1°C

Portsea

⭐ 4.8/5

19.5°C

London Bridge Lookout

⭐ 2.9/5

17.8°C

London Bridge Beach 2

⭐ 2.9/5

19.1°C

London Bridge Beach 1

⭐ 2.9/5

19.3°C

Beach 274

⭐ 2.9/5

19.3°C

Beach 273

⭐ 2.9/5

19.5°C

Swimming Conditions

Swimming in Portsea is allowed and offers a clear contrast between calm and challenging conditions. Inside Port Phillip Bay, beaches are relatively sheltered, with smaller waves and gentler water that suits families and relaxed swimmers, particularly in summer when the water is at its warmest. Closer to the heads and the open Bass Strait, currents can be strong and conditions change quickly, making swimming better suited to confident and experienced swimmers only. On calm days, the water is clean and clear, and swimming can be very enjoyable. In cooler months, most locals keep swims brief or rely on wetsuits. Overall, Portsea provides clean water, noticeable seasonal temperature changes, and a mix of easy bay swimming and more demanding open-water conditions depending on location and weather.