Castles (Cactus)
Hourly
Confidence
Compare
⏱️s.
⚡️kJ
Saturday 13
Sunday 14
Monday 15
Tuesday 16
Wednesday 17
Timezone:
Australia/Adelaide
Wind: ⭐ UNIFIED
(20251213 16z)
Waves: ⭐ UNIFIED
(20251213 16z)
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Castles (Cactus) surf forecast characteristics

Swell window
S - W
(Best from SW)
Swell size
3ft - 12ft
Swell breaks over
Uneven Reef
Wave types
Reef
Wave directions
Left
Wind window
NE - NE
(Offshore from NE)
Works at
Low, Mid
Skill Level
Expert

Castles (Cactus) surf forecast guide

Castles, also known as Cactus, sits in the middle of the bay and is a spot that offers a mixed bag of surfing experiences, depending on the day. On smaller days, you can find some zippery reform waves inside, while on bigger days, it comes alive with more powerful and meaty barrels out the back. If you're looking to surf here, aim for swells coming from the southwest, as they tend to be the best. The spot can hold swells around 3 ft (about 0.9 m) and keeps breaking through all but high tide.

When you're out at Castles, you'll find that the waves break over an uneven reef, producing mainly lefts. It's a pretty heavy spot that requires expert skills to tackle, thanks to its powerful waves and significant shark presence. The best wind conditions come from the northeast, and the ideal tides for surfing are low to mid. It's a place for experienced surfers looking for a rush, so make sure you're ready for what the ocean has in store.

One thing to keep in mind is the nearby deep channel, which is known to be a breeding ground for Bronze Whalers and a hunting ground for Great White Sharks. This area has seen its fair share of shark bites, including some notable incidents with local surfers, so it's best to stay alert while enjoying the waves. With all that said, Castles is definitely a spot for those who know what they're doing and want to experience some serious surf.

Surf schools and rentals

Surf reports and surf forecasts nearby Castles (Cactus)

Caves
South Australia, Australia
Reef break
Sat 13
Sun 14
Mon 15
Tue 16
Wed 17
Castles (Cactus)
South Australia, Australia
Reef break
Sat 13
Sun 14
Mon 15
Tue 16
Wed 17
Cactus
South Australia, Australia
Reef break
Sat 13
Sun 14
Mon 15
Tue 16
Wed 17
Crushers
South Australia, Australia
Reef break
Sat 13
Sun 14
Mon 15
Tue 16
Wed 17
Cunns
South Australia, Australia
Reef break
Sat 13
Sun 14
Mon 15
Tue 16
Wed 17
Confidence

Confidence tells you how much the weather models agree on the forecast.

  • High confidence: Models agree closely; forecast is reliable.
  • Medium confidence: Some disagreement; conditions may shift slightly.
  • Low confidence: Models diverge; treat forecast with caution.

We calculate the wind confidence by comparing wind speed, gust and direction from multiple models (like GFS, ECMWF, Arome, and Harmonie) and seeing how closely they match. For wave certainty we compare height, period and direction, also on multiple models. They are weighted, meaning that some models count more than others, depending on how good they are for a certain spot.

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Readme

Welcome! If you’re new to surf forecasting, check out this quick guide.

Forecast Table

The forecast table (the section on the page with all the numbers) is designed to pack as much information in the screen as possible. Although intimidating at first, it will help you make informed decisions about the waves faster, trust me :D. The table consists of roughly four sections, time and predictions, wind, waves, and tides:

🔮 Time and predictions section

Here we show the forecast thour and the overall surf quality prediction. This is determined based on the wave, wind and tide quality prediction. These individual predictions can be found on the forecast map.

💨 Wind section

The first row on the table (with the 💨 icon) shows wind speed, direction and gust. The more the wind speed the more aggressive the color (from blue, green, orange to red).

🌊 Wave section

The waves section consists of three rows, one for wave height and direction, one for period and one for wave energy. Our algorithm choices the "dominant wave". This is normally the first swell partition, but with heavy local storms it displays the wind waves. If that's the case, we display the numbers in italic and in gray.

🌒 Tide section

The tide section consists of a row with the actual heights per hour (measured at the half hour) and a table that displays the flow of the tide and the extremes (lows and highs).

Forecast map

The forecast map consists of arrows. These arrows represent all wave partitions (swell partitions and wind wave partition) and the wind. This allows you to see things like: a secondary swell or wind waves messes up the surf, or the wind is just a tick offshore so very surfable. Click a metric label in the bottom left to bring that arrow to the front — handy when arrows overlap.

Forecast Cheat Sheet

Short on time? Focus on wave energy. It’s the best single metric to gauge how big and powerful the waves will be.

Click any table cell to jump to that forecast hour. The map will update with forecast arrows, so you can see if wind and swell direction are lining up.

Use the table sidebar to switch units for height and speed.

Log your surf sessions to compare forecasts with real sessions and sharpen future predictions.

Models and Updates

Surfnerd blends multiple global and local wind and swell models using advanced interpolation and spatial techniques to create an "ensemble" forecast. Forecasts are refreshed hourly.

Surf Predictions

Our AI-driven algorithm scores surf quality, shown by green, orange, and gray dots. Each forecast hour is rated for wind, swell, and tide quality, then combined into an overall score. Here’s the scale:

Perfect
Good
Average
Bad or No Data

Session logs also feed the algorithm — the more you log, the smarter your forecasts get.

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