Portsea – current water temperature and swimming conditions

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

⚠️ This is cool water that may feel brisk on entry. Swimming is usually limited to short sessions, and prolonged stays can become uncomfortable without thermal protection. Many swimmers choose a wetsuit, especially for surfing or open-water swimming.

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

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 16.7°C in the next 7 days. See the table below for daily data for the upcoming week.

Table of Daily Sea Temperature Data

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.