Castle Rock – current water temperature and swimming conditions

This page shows the current water temperature at Castle Rock in Western Australia. 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

20.9°C

Today

20.6°C

Yesterday

20.9°C

A Week Ago

The average sea water temperature today in Castle Rock is about 21°C.

Water Temperature in Castle Rock: Daily Trends, Historical Records, and Forecast

✅ This water feels mild to warm and is comfortable for the majority of swimmers. Swimming is enjoyable, though longer stays may feel cooler for some people, especially in windy conditions. These temperatures are well suited to family outings and active swimming, particularly on warm days.

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 Castle Rockfell over the past month, but have levelled out during the last week.

According to our forecast, Sea water temperature in Castle Rock will be 22.2°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	21.4°C	21.5°C
Mar 13	21.4°C	21.8°C
Mar 14	20.9°C	21.5°C
Mar 15	20.8°C	21.5°C
Mar 16	20.7°C	22.0°C
Mar 17	20.6°C	22.0°C
Mar 18	20.6°C	21.8°C
Mar 19	20.6°C	22.0°C
Mar 20	20.9°C	22.0°C	20.9°C
Mar 21		22.3°C	21.1°C
Mar 22		22.3°C	21.3°C
Mar 23		22.8°C	21.5°C
Mar 24		21.8°C	21.7°C
Mar 25		22.3°C	21.9°C
Mar 26		22.8°C	22.0°C
Mar 27		22.3°C	22.2°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 Castle Rock 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

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.

Monthly Water Temperature Range (Min, Max & Average)

Month	Min	Avg	Max
January	18°C	21°C	23°C
February	19°C	21°C	24°C
March	19°C	22°C	25°C
April	18°C	22°C	24°C
May	19°C	21°C	24°C
June	17°C	20°C	22°C
July	16°C	20°C	21°C
August	17°C	18°C	20°C
September	16°C	18°C	20°C
October	16°C	18°C	20°C
November	16°C	19°C	21°C
December	17°C	20°C	23°C

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

Castle Rock: Weather Forecast

March 21

16°C / 27°C

few clouds: 11-25%

humidity: 72% | wind: 25 kmh

March 22

17°C / 27°C

clear sky

humidity: 64% | wind: 29 kmh

March 23

15°C / 25°C

clear sky

humidity: 70% | wind: 25 kmh

Local Water Conditions and Nearby Spots

Nearby Beaches and Water Temperatures

Castle Rock Beach

⭐ 2.8/5

20.7°C

Curtis Bay Beach

⭐ 3.1/5

20.8°C

Meelup Bay

⭐ 4.4/5

21.2°C

Meelup Beach

⭐ 5.0/5

20.9°C

Dunsborough Beach

⭐ 5.0/5

22.1°C

Eagle Bay

⭐ 3.9/5

21.1°C

Quindalup Beach

⭐ 4.6/5

21.3°C

Three Bears

⭐ 3.2/5

21.6°C

Leeuwin-Naturaliste National Park

⭐ 3.1/5

20.5°C

Swimming Conditions

Swimming at Castle Rock is allowed, but conditions vary depending on swell and wind. The surrounding rock formations can provide some shelter, creating calmer water on the right day, especially in summer when seas are generally lighter. These sheltered pockets suit confident swimmers looking for a refreshing dip rather than long, relaxed swims. When swell is running, waves and currents can be strong, making swimming less suitable and requiring caution. In summer, many people swim without wetsuits, while spring and autumn usually suit shorter dips. Winter swimming is mostly for locals accustomed to cooler water or those wearing thermal gear. Overall, Castle Rock offers a more natural, changeable swimming experience, best enjoyed by swimmers who read conditions carefully and respect the open Indian Ocean environment.