Surf Forecasts:
Castles Beach surf forecast from 18 Aug 2026:
- Best quality surf: Thursday 20 Aug, 11PM (local time) - 2.5ft (0.8m), 7s period, E swell with glassy winds.
- Most powerful swell: Monday 24 Aug, 8PM (local time) - 7.5ft (2.3m), 7s period, ENE swell with 557 kJ wave energy.
- Next surfable swell (1★+): Thursday 20 Aug, 11PM (local time) - 2.5ft (0.8m), 7s period with E swell.
Best Forecast Surf Conditions for Castles Beach this week:
The surf forecast for Castles Beach over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Thursday (Aug 20) at 11PM. The primary swell is predicted to be 0.8m and 7s period with a secondary swell of 0.7m and 7s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Castles Beach in the next 16 days are 2.3m 7s and forecast to arrive on Monday (Aug 24) at 8PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 13s period and expected on Sunday (Aug 23) at 2AM.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 11PM (Thu 20th Aug) | 2.5ft (0.8m) 7s |
| Best Surf | 11PM (Thu 20th Aug) | 2.5ft (0.8m) 7s |
| Most Powerful | 8PM (Mon 24th Aug) | 7.5ft (2.3m) 7s |
Table - best surf conditions forecast for Castles Beach over the next 16 days.
Short Range ForecastMostly dry. Warm (max 25°C on Mon afternoon, min 24°C on Tue night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 26°C on Fri afternoon, min 24°C on Thu night). Winds increasing (calm on Thu night, fresh winds from the ENE by Sat night). | |||||||||||||||||||
Mon 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | ||||||||||||||
PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | |
Swell Height Map |  |  |  |  |  |  |  | |||||||||||||
Wave Height (m) Direction Period (s) | ENE 7 | ENE 7 | ENE 7 | ENE 6 | ENE 5 | E 8 | E 8 | E 8 | E 8 | E 7 | E 7 | E 7 | ENE 7 | ENE 7 | ENE 6 | ENE 6 | ENE 7 | ENE 7 | ENE 6 | ENE 7 |
Wave Graph  | ||||||||||||||||||||
 kJ | 261 | 173 | 139 | 119 | 102 | 113 | 84 | 82 | 74 | 70 | 68 | 48 | 113 | 102 | 115 | 150 | 330 | 257 | 164 | 317 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | on | cross-on | on | on | cross-on | cross-on | cross-on | cross-on | glassy | on | on | on | on | cross-on | on | cross-on | cross-on | cross-on |
High Tide | 4:33PM0.62m | 7:01AM0.60m | 4:19PM0.57m | 8:55AM0.61m | 11:13AM0.64m | 12:09PM0.69m | 12:42PM0.74m | 9:57PM0.37m | 1:10PM0.78m | 11:42PM0.41m | ||||||||||
Low Tide | 11:37PM0.19m | 11:57AM0.50m | 00:07AM0.20m | 00:51AM0.22m | 2:10AM0.23m | 3:54AM0.21m | 9:32PM0.37m | 5:06AM0.18m | 8:28PM0.36m | |||||||||||
 |  |  | | | | | | | |  | | | | | | | | |  | |
 | — | — | 6:09 | — | — | 6:09 | — | — | 6:09 | — | — | 6:11 | — | — | 6:11 | — | — | 6:11 | — | — |
 | 6:59 | — | — | 6:59 | — | — | 6:58 | — | — | 6:57 | — | — | 6:55 | — | — | 6:55 | — | — | 6:54 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 |
Temp °C | 25 | 25 | 25 | 25 | 25 | 24 | 25 | 25 | 25 | 25 | 25 | 25 | 26 | 26 | 26 | 26 | 25 | 25 | 25 | 25 |
Feels °C | 25 | 25 | 24 | 24 | 24 | 24 | 26 | 27 | 27 | 27 | 27 | 28 | 28 | 29 | 27 | 26 | 25 | 24 | 23 | 23 |
Swell 1 Height (m) Direction Period (s) | S 14 | S 13 | S 13 | S 13 | S 13 | NE 6 | E 8 | E 8 | E 8 | E 7 | E 7 | E 7 | E 8 | E 8 | ESE 8 | SSW 16 | NW 13 | NW 12 | ESE 9 | NW 11 |
| kJ | 65 | 55 | 54 | 30 | 29 | 51 | 84 | 82 | 74 | 70 | 68 | 48 | 12 | 12 | 23 | 25 | 41 | 35 | 113 | 30 |
Swell 2 Height (m) Direction Period (s) | S 6 | E 9 | SW 17 | NE 8 | NNE 7 | S 12 | NE 6 | NE 6 | NE 6 | NNE 7 | NNE 7 | NNE 6 | SSW 16 | SSW 16 | SSE 15 | S 12 | SSE 14 | SSE 13 | NW 11 | SSE 13 |
| kJ | 5 | 7 | 11 | 10 | 5 | 11 | 40 | 40 | 39 | 38 | 40 | 36 | 27 | 50 | 42 | 12 | 41 | 35 | 31 | 34 |
Swell 3 Height (m) Direction Period (s) | N 7 | N 7 | N 7 | SW 18 | S 6 | SSE 9 | S 12 | S 12 | SSW 18 | SSW 18 | SSW 17 | SSW 17 | SSE 8 | S 13 | SSW 16 | SSE 15 | SSW 16 | ESE 11 | SSW 15 | SSW 14 |
| kJ | 1 | 1 | 1 | 12 | 1 | 8 | 11 | 11 | 31 | 30 | 27 | 29 | 7 | 14 | 26 | 21 | 24 | 23 | 22 | 21 |
Wind waves Height (m) Direction Period (s) | ENE 7 | ENE 7 | ENE 7 | ENE 6 | ENE 5 | E 8 | — | — | — | — | — | ENE 7 | ENE 7 | ENE 7 | ENE 6 | ENE 6 | ENE 7 | ENE 7 | ENE 6 | ENE 7 |
| kJ | 261 | 173 | 139 | 119 | 102 | 113 | — | — | — | — | — | 36 | 113 | 102 | 115 | 150 | 330 | 257 | 164 | 317 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 18 | 18 | 41 | 41 | 18 | 19 | 18 | 18 | 18 | 18 | 0 | 18 | 18 | 18 | 18 | 41 | 41 | 41 | 123 | 41 |
Best forecast wave conditions in Oahu | ||||||||||||||||||||
Best forecast wave conditions in United States | ||||||||||||||||||||
Header Global | ||||||||||||||||||||
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FREE! Surf-Forecast.com widget for your website
The surf report / weather widget below is available to embed on third party websites free of charge and provides a summary of our Castles Beach surf forecast. Simply grab the html code snippet that we provide and paste it into your own site. You can choose your preferred language and metric/imperial units for the surf forecast feed to suit users of your site. Click here to get the code.
Information about the Castles Beach Surf forecast
The above surf forecast table for Castles Beach provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Castles Beach can be found by selecting the local surf guide option on the grey menu. Our Castles Beach surf forecast is unique since it includes wave energy (power) that defines the real feel of the surf rather than just the height or the period. If you surf the same spot (Castles Beach) regularly then make a mental note of the wave energy from the surf forecast table each time you go. Very soon you may start to choose your surf days based on the wave energy alone combined with our forecast of favourable offshore wind conditions. Our star ratings will help here and of course you will also find the usual wave height and period predictions on our surf forecasts as well as a full break down of the swell components under our advanced users option (to reveal that, click the little Einstein character under the tide times).
Further information to help with frequently asked questions about our surf forecast for Castles Beach may be found under the help tab on the top menu and also by moving your mouse over the question marks on the surf forecast table itself. Please always bear in mind that the forecast is for near-shore open water and local factors at each surf break influence the actual breaking wave height, such as the beach / reef profile, water depths offshore and shelter.
Castles is 2 km (1 miles) from Kailua. If you plan a vacation in Oahu, look for hotels and other accommodation in Kailua. Kailua has rooms for a wide range of budgets as well as car hire and transport links.
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