Surf Forecasts:
Rock Island surf forecast from 14 Aug 2026:
- Best quality surf: Saturday 15 Aug, 12AM (local time) - 1ft (0.3m), 10s period, SSE swell with cross-offshore winds.
- Most powerful swell: Saturday 15 Aug, 3PM (local time) - 2.5ft (0.8m), 9s period, ESE swell with 103 kJ wave energy.
- Next surfable swell (1★+): Saturday 15 Aug, 12AM (local time) - 1ft (0.3m), 10s period with SSE 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 Saturday (Aug 15) at 12AM. The primary swell is predicted to be 0.3m and 10s period with a secondary swell of 0.3m and 9s. Another secondary swell of 0.4m and 5s is also forecast. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Rock Island in the next 16 days are 0.8m 9s and forecast to arrive on Saturday (Aug 15) at 3PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.5m 6s period and expected on Thursday (Aug 20) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12AM (Sat 15th Aug) | 1ft (0.3m) 10s |
| Best Surf | 12AM (Sat 15th Aug) | 1ft (0.3m) 10s |
| Most Powerful | 3PM (Sat 15th Aug) | 2.5ft (0.8m) 9s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright, grab a coffee and settle in. This is a pretty flat one for now.
No lies, the next week or so is a write-off for any kind of real surf. We’re looking at a stretch of weak, short-period leftovers that are just too small and sloppy to even think about paddling out. Winds will be mostly okay, but with swell hovering around a pathetic 1ft to 2ft and combined wave energy barely cracking double digits (like 19), you’re better off sorting your gear. The water temp is sitting at 81°, which is just normal for this time of year, but that’s about the only thing that’s normal – the surf is not.
The only small glimmer in this entire 16-day window lands on Monday, August 24th. Rock Island finally gets a bump of real groundswell, coming from the SE with a 4ft face and a nice long 16-second period. The combined energy jumps up to 683 – that’s proper, solid energy for this setup. The morning session on Monday is the standout. We’re looking at clean lines, with a light cross-offshore breeze. This could actually get good. Remember, that long period (groundswell) tends to favour point breaks and reefs over beach breaks, so Rock Island as a reef should handle it nicely. However, that afternoon the wind swings onshore, so it’s a morning mission or nothing.
After that little spike, it drops straight back into the doldrums. We’re talking 1ft dribble again by the end of the week.
So, there it is. A long dry spell, one real opportunity on the 24th, then back to flatness. Forecasts can change though, it doesn’t usually stay this poor for this long around here.
Rusty
Short Range ForecastHeavy rain (total 22mm), heaviest during Fri night. Warm (max 29°C on Fri afternoon, min 24°C on Sat night). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 6mm), mostly falling on Mon morning. Warm (max 30°C on Tue afternoon, min 25°C on Mon night). Wind will be generally light. | ||||||||||||||||||||
Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | |||||||||||||||
AM | 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) | SSW 9 | SSW 9 | SSE 10 | SSW 11 | ESE 9 | SE 8 | SSW 9 | S 9 | S 9 | S 9 | S 8 | SE 5 | SE 6 | SE 7 | SSE 8 | SE 7 | SSE 7 | SSE 7 | SSE 7 | SSW 11 | S 9 |
Wave Graph  | |||||||||||||||||||||
 kJ | 16 | 29 | 20 | 40 | 103 | 29 | 28 | 39 | 37 | 23 | 22 | 7 | 9 | 11 | 44 | 27 | 20 | 29 | 21 | 22 | 64 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | cross | cross-off | cross-off | cross-on | cross-off | off | cross-off | cross-off | cross-off | cross-on | cross-off | off | cross-off | off | off | off | off | off | cross-off | cross-off |
High Tide | 6:31PM1.48m | 5:41AM1.56m | 6:55PM1.48m | 6:26AM1.55m | 7:18PM1.48m | 7:12AM1.50m | 7:41PM1.48m | 8:00AM1.43m | 8:06PM1.47m | 8:53AM1.34m | 8:32PM1.46m | 9:59AM1.24m | 9:00PM1.45m | ||||||||
Low Tide | 11:48AM0.17m | 00:00AM0.78m | 12:23PM0.24m | 00:35AM0.68m | 12:57PM0.34m | 1:12AM0.59m | 1:28PM0.46m | 1:51AM0.52m | 1:59PM0.61m | 2:34AM0.48m | 2:29PM0.75m | 3:23AM0.45m | 3:00PM0.90m | ||||||||
 | |  |  |  |  | | |  |  | |  | |  | | | | | | | | |
 | 4:58 | — | — | 5:00 | — | — | 5:01 | — | — | 5:01 | — | — | 5:01 | — | — | 5:03 | — | — | 5:03 | — | — |
 | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:29 | — | — | 6:28 | — | — | 6:27 | — | — | 6:24 | — |
mm | 1 | 4 | 14 | — | — | — | — | — | 3 | 1 | — | — | — | 1 | 2 | — | 1 | 1 | — | — | — |
Temp °C | 28 | 29 | 27 | 28 | 29 | 25 | 27 | 29 | 26 | 27 | 28 | 26 | 28 | 30 | 26 | 28 | 30 | 26 | 27 | 28 | 25 |
Feels °C | 30 | 31 | 30 | 29 | 30 | 26 | 27 | 30 | 28 | 30 | 31 | 28 | 27 | 30 | 27 | 28 | 31 | 27 | 28 | 30 | 25 |
Swell 1 Height (m) Direction Period (s) | SSW 9 | SSW 9 | SSW 9 | SSW 11 | SE 8 | SE 8 | SSW 9 | S 9 | S 9 | S 9 | S 8 | SE 5 | SE 6 | SE 7 | SSE 8 | SE 7 | SSE 7 | SSE 7 | SSE 7 | SSE 7 | S 9 |
| kJ | 16 | 29 | 16 | 40 | 33 | 29 | 28 | 39 | 37 | 23 | 22 | 7 | 9 | 11 | 44 | 27 | 20 | 29 | 21 | 21 | 64 |
Swell 2 Height (m) Direction Period (s) | ESE 6 | SE 11 | SSE 10 | SE 5 | SSW 10 | SSW 9 | SE 7 | SSE 11 | SE 11 | SE 11 | SSE 11 | SSW 8 | SSW 8 | SSE 10 | SE 10 | SE 10 | SSE 10 | SSW 8 | S 10 | SSW 11 | SE 10 |
| kJ | 4 | 5 | 20 | 10 | 34 | 28 | 14 | 12 | 19 | 18 | 11 | 7 | 6 | 10 | 4 | 4 | 9 | 6 | 8 | 22 | 4 |
Swell 3 Height (m) Direction Period (s) | S 12 | S 8 | S 12 | SSE 9 | SE 10 | SE 12 | SSE 12 | E 10 | E 9 | — | E 9 | SE 11 | SE 10 | SSW 8 | SW 8 | SW 9 | SW 8 | S 12 | SE 10 | SE 10 | SE 11 |
| kJ | 11 | 1 | 11 | 16 | 4 | 6 | 14 | 2 | 1 | — | 1 | 4 | 4 | 6 | 2 | 3 | 3 | 3 | 4 | 4 | 29 |
Wind waves Height (m) Direction Period (s) | NNE 3 | ESE 6 | SE 5 | — | ESE 9 | — | — | — | — | — | — | — | — | — | ENE 2 | NE 3 | NE 3 | ENE 2 | ENE 3 | ESE 6 | — |
| kJ | 3 | 7 | 7 | — | 103 | — | — | — | — | — | — | — | — | — | 1 | 2 | 2 | 1 | 1 | 18 | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 38 | 64 | 0 | 0 | 491 | 0 | 0 | 0 | 0 | 38 | 16 | 64 | 51 | 470 | 0 | 86 | 38 | 38 | 51 | 885 | 12 |
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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