Surf Forecasts:
Rock Island surf forecast from 24 Aug 2026:
- Best quality surf: Thursday 27 Aug, 12PM (local time) - 1.5ft (0.5m), 12s period, SW swell with offshore winds.
- Most powerful swell: Monday 24 Aug, 9PM (local time) - 5ft (1.6m), 14s period, SSE swell with 994 kJ wave energy.
- Next surfable swell (1★+): Thursday 27 Aug, 12PM (local time) - 1.5ft (0.5m), 12s period with SW swell.
Best Forecast Surf Conditions for Rock Island this week:
The surf forecast for Rock Island over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Thursday (Aug 27) at 12PM. The primary swell is predicted to be 0.5m and 12s period with a secondary swell of 0.5m and 6s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Rock Island in the next 16 days are 1.6m 14s and forecast to arrive on Monday (Aug 24) at 9PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 3s period and expected on Thursday (Aug 27) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12PM (Thu 27th Aug) | 1.5ft (0.5m) 12s |
| Best Surf | 12PM (Thu 27th Aug) | 1.5ft (0.5m) 12s |
| Most Powerful | 9PM (Mon 24th Aug) | 5ft (1.6m) 14s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s have a look at what’s coming down the line for Rock Island. I gotta be straight with you – the next week and a half is a bit of a tough stretch. The forecast is mostly a string of poor surf conditions, with onshore breezes messing things up. The water temp is sitting at 82°F, which is about normal for this time of year, so at least the water’s warm while you’re waiting.
We’ve got a real gap here. From Monday the 24th of August all the way through to Thursday the 3rd of September, there’s basically nothing worth paddling out for. The swell energy is weak, dropping from a moderate 830 into the low hundreds and then down to double digits. It’s a long, quiet stretch.
The first real glimmer of hope shows up on Thursday morning, the 3rd of September. Rock Island (reef) will see a clean 3ft south swell with a period of 11 seconds, and a cross-offshore breeze. The combined energy is 272, which is moderate. It’s still a bit small, but it's the first sign of life.
Now, the standout period is Friday the 4th of September. That’s the one to circle on the calendar. The morning brings a 4ft SSW groundswell with a 13-second period, a gentle offshore wind from the NE, and the waves are clean. The combined energy jumps to 598. Then Friday afternoon gets even better: 5ft from the SSW, a 14-second period, glassy conditions, and a combined energy of 764. That’s the real deal – clean, shoulder-to-head high waves with that long period energy. This is a reef break, so that long period swell will wrap in nicely.
Saturday the 5th of September is a mixed bag. The morning is a write-off with heavy rain and a strong 25 mph cross-onshore wind blowing out a 5ft swell. But the afternoon clears up: a 5ft south swell with a 12-second period, combined energy of 799, and a clean cross-offshore breeze. That’s another solid session if you can wait out the morning.
After that, the swell hangs around but the winds get messy again. The 6th of September sees a 7ft south swell, but the cross-onshore wind makes it choppy. That’s expert territory anyway, so be careful.
So, to sum it up: the best surf on offer is hands-down Friday the 4th of September, with the afternoon glass-off being the pick of the bunch. Saturday the 5th afternoon is also a winner. Everything else is either too small, windy, or just plain average. Keep your eyes on the sky for that Friday.
Rusty.
Short Range ForecastLight rain (total 2mm), mostly falling on Thu morning. Warm (max 31°C on Wed afternoon, min 27°C on Mon night). Winds decreasing (fresh winds from the SW on Wed afternoon, light winds from the SW by Thu morning). | Days 5-7 Weather SummaryModerate rain (total 12mm), heaviest on Sat night. Warm (max 28°C on Fri afternoon, min 23°C on Thu night). Winds decreasing (fresh winds from the NNE on Thu afternoon, calm by Fri night). | |||||||||||||||||||
Mon 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | ||||||||||||||
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) | SSE 16 | SSE 14 | SSE 13 | SSE 12 | S 12 | SSW 12 | SSW 13 | SSW 12 | SW 12 | S 11 | S 10 | S 9 | S 8 | S 8 | S 6 | SSW 8 | SSW 8 | SSW 8 | SSW 8 | SSE 10 |
Wave Graph  | ||||||||||||||||||||
 kJ | 480 | 815 | 690 | 298 | 400 | 258 | 289 | 125 | 67 | 55 | 45 | 39 | 50 | 45 | 22 | 21 | 13 | 12 | 11 | 10 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | on | on | on | on | on | cross-on | cross-on | off | on | off | cross-on | glassy | off | cross-off | off | off | cross-off | cross-off |
High Tide | 4:17PM1.34m | 1:21AM1.36m | 4:45PM1.39m | 2:39AM1.41m | 5:10PM1.43m | 3:40AM1.47m | 5:33PM1.46m | 4:32AM1.53m | 5:56PM1.47m | 5:19AM1.57m | 6:18PM1.49m | 6:04AM1.58m | 6:41PM1.49m | |||||||
Low Tide | 8:44PM1.17m | 9:11AM0.27m | 9:41PM1.08m | 10:00AM0.23m | 10:21PM0.97m | 10:42AM0.22m | 10:57PM0.85m | 11:20AM0.24m | 11:30PM0.73m | 11:54AM0.30m | 00:05AM0.62m | 12:27PM0.39m | 00:39AM0.52m | |||||||
 |  | | | | | |  |  |  |  |  | |  |  | | | | | | |
 | — | — | 5:07 | — | — | 5:07 | — | — | 5:09 | — | — | 5:09 | — | — | 5:11 | — | — | 5:11 | — | — |
 | 6:20 | — | — | 6:19 | — | — | 6:17 | — | — | 6:15 | — | — | 6:15 | — | — | 6:14 | — | — | 6:12 | — |
mm | — | — | — | — | — | — | — | — | 2 | 3 | 1 | — | — | 1 | — | 2 | 5 | — | — | — |
Temp °C | 28 | 27 | 29 | 29 | 27 | 29 | 31 | 28 | 29 | 24 | 24 | 26 | 28 | 27 | 28 | 28 | 24 | 27 | 29 | 26 |
Feels °C | 29 | 28 | 29 | 29 | 27 | 31 | 32 | 28 | 34 | 23 | 27 | 28 | 31 | 31 | 30 | 30 | 25 | 28 | 31 | 29 |
Swell 1 Height (m) Direction Period (s) | SSE 13 | SSE 14 | SSE 13 | SSE 12 | S 12 | SSW 12 | SSW 13 | SSW 12 | S 6 | S 11 | S 10 | S 9 | SSE 9 | S 8 | S 6 | SSW 8 | SSW 8 | SSW 8 | SSW 8 | SSW 8 |
| kJ | 342 | 815 | 690 | 298 | 400 | 258 | 289 | 125 | 25 | 55 | 45 | 39 | 8 | 45 | 22 | 21 | 13 | 12 | 11 | 6 |
Swell 2 Height (m) Direction Period (s) | SSE 16 | S 17 | E 14 | S 14 | E 13 | SSE 9 | SSE 9 | SSE 9 | SW 12 | SSW 12 | SW 11 | SSE 9 | SW 10 | SSE 10 | SSE 11 | SSE 11 | SSE 10 | SSE 10 | SSE 10 | SSE 10 |
| kJ | 480 | 351 | 4 | 243 | 3 | 48 | 32 | 32 | 67 | 53 | 19 | 8 | 4 | 9 | 11 | 12 | 10 | 10 | 10 | 10 |
Swell 3 Height (m) Direction Period (s) | SW 8 | ESE 15 | ESE 14 | E 13 | ESE 13 | E 12 | E 12 | S 11 | SSE 9 | SSW 6 | SSE 10 | SW 10 | SE 15 | SW 9 | SSW 9 | E 6 | — | SW 9 | SW 11 | SW 10 |
| kJ | 3 | 42 | 66 | 3 | 33 | 3 | 3 | 20 | 28 | 10 | 9 | 4 | 8 | 3 | 8 | 3 | — | 3 | 4 | 4 |
Wind waves Height (m) Direction Period (s) | S 3 | SW 4 | SSW 4 | SSW 4 | SSW 5 | SSW 5 | SSW 5 | SSW 6 | — | NNE 3 | — | — | S 8 | — | NE 3 | NE 3 | — | — | — | S 2 |
| kJ | 5 | 13 | 6 | 43 | 25 | 8 | 45 | 53 | — | 2 | — | — | 50 | — | 2 | 1 | — | — | — | 1 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 518 | 14 | 14 | 491 | 27 | 14 | 518 | 27 | 8 | 55 | 14 | 0 | 76 | 0 | 51 | 51 | 54 | 38 | 16 | 38 |
Best forecast wave conditions in Kanagawa | ||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||
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Information about the Rock Island Surf forecast
The above surf forecast table for Rock Island provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Rock Island can be found by selecting the local surf guide option on the grey menu. Our Rock Island 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 (Rock Island) 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 Rock Island 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.
Rock Island is 3 km (2 miles) from the city of Kamakura. If you plan a holiday in Kanagawa, look for hotels and other accommodation in Kamakura. Kamakura has rooms for a wide range of budgets as well as car hire and transport links.
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