Rottnest Island – current water temperature and swimming conditions

Water Temperature in Rottnest Island: 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

While water temperatures in Rottnest Island declined overall during the past month, they have shown a noticeable rebound over the last week.

According to our forecast, Sea water temperature in Rottnest Island will be 18.7°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

Rottnest Island sits just offshore from Perth and is famous for its clear water, sheltered bays, and some of the best swimming conditions in Western Australia. Water temperatures here are generally a touch warmer than the mainland coast. In summer, from December to February, the sea usually ranges between 22–25°C, feeling warm and very comfortable for long swims. Autumn remains inviting at around 20–23°C, while winter cools to roughly 17–19°C, which is still manageable for short swims. Spring brings a steady warm-up again, typically sitting between 19–22°C as the weather improves.