Castle Rock – current water temperature and swimming conditions

Water Temperature in Castle Rock: 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 Castle Rock 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 Castle Rock will be 18.0°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

Castle Rock lies along the Margaret River coastline, where rocky headlands and pockets of sand meet the Indian Ocean. Water temperatures here follow the familiar south-west pattern. In summer, from December to February, the sea usually sits around 19–22°C, which feels comfortable on warm, settled days. Autumn cools gradually to about 17–20°C, while winter is noticeably colder and brisk, typically around 14–16°C. Spring brings a slow warm-up again to roughly 16–18°C, though on windy days the water can feel cooler than the figures suggest.