Surf Forecasts:
Rock Island surf forecast from 11 Aug 2026:
- Best quality surf: Wednesday 12 Aug, 3PM (local time) - 1.5ft (0.5m), 10s period, SSW swell with cross-offshore winds.
- Most powerful swell: Saturday 15 Aug, 9PM (local time) - 3ft (0.9m), 10s period, ESE swell with 159 kJ wave energy.
- Next surfable swell (1★+): Wednesday 12 Aug, 3PM (local time) - 1.5ft (0.5m), 10s period with SSW 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 Wednesday (Aug 12) at 3PM. The primary swell is predicted to be 0.5m and 10s period with a secondary swell of 0.1m and 12s. Another secondary swell of 0.5m 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 0.9m 10s and forecast to arrive on Saturday (Aug 15) at 9PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 3s period and expected on Friday (Aug 14) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Wed 12th Aug) | 1.5ft (0.5m) 10s |
| Best Surf | 3PM (Wed 12th Aug) | 1.5ft (0.5m) 10s |
| Most Powerful | 9PM (Sat 15th Aug) | 3ft (0.9m) 10s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s get into it.
Well, it’s a bit of a slow start for the Rock Island area. We’re looking at a long stretch of pretty ordinary conditions, with a real gap in quality surf from now until about the 27th of August. The first week or so is mostly tiny, weak swells with a lot of onshore wind, so don’t expect much to ride.
The first real sign of life is on the morning of Thursday, 27 August. That’s the standout window. Rock Island (reef) will see a clean 3ft swell from the south, with a gentle offshore breeze from the ENE. The period is 11 seconds, so it’s a proper groundswell, with good shape and energy. The combined energy is at 248 (moderate), so there’s enough power for a fun session. The early morning glass-off will have it looking clean. This is your best bet by a long shot.
Before that, the morning of Saturday, 22 August is worth a mention. There’s a glassy morning with a 2ft south swell, period 10 seconds. The energy is weak at 54, but it’s surfable and clean. It’s a tiny wave, but if you’re desperate you might find a fun one.
The rest of the window is a write-off with onshore winds, tiny lumps, and poor surf. The 26th of August sees a jump in energy to 157 (moderate) from a long-period 13-second south swell, but the wind is cross-onshore and choppy, spoiling it all.
So, for the best on offer, pencil in the 27th of August. It’s not a massive swell, but with the clean offshore wind, it’ll be the most fun you’ll have in this stretch.
Rusty.
Short Range ForecastHeavy rain (total 93mm), heaviest during Tue night. Warm (max 29°C on Fri afternoon, min 23°C on Wed night). Winds decreasing (fresh winds from the SSW on Tue night, light winds from the NE by Thu afternoon). | Days 5-7 Weather SummaryHeavy rain (total 24mm), heaviest during Fri night. Warm (max 28°C on Sat afternoon, min 23°C on Sun night). Wind will be generally light. | ||||||||||||||||||
Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | ||||||||||||||
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 5 | S 10 | SSW 10 | SSW 10 | SSW 10 | S 10 | SSW 9 | SSW 9 | SSW 9 | S 12 | S 11 | S 10 | S 9 | SSW 9 | SSW 9 | SSW 9 | SSW 10 | SSW 9 | SSW 9 |
Wave Graph  | |||||||||||||||||||
 kJ | 91 | 130 | 59 | 39 | 38 | 47 | 28 | 28 | 28 | 45 | 61 | 51 | 41 | 27 | 28 | 28 | 31 | 16 | 15 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross | cross-off | off | off | cross-off | off | off | cross-off | off | off | cross-off | off | off | cross-off | cross-off | cross-off | on | cross-on |
High Tide | 3:09AM1.45m | 5:43PM1.45m | 4:05AM1.50m | 6:08PM1.47m | 4:55AM1.54m | 6:31PM1.48m | 5:41AM1.56m | 6:55PM1.48m | 6:26AM1.55m | 7:18PM1.48m | 7:12AM1.50m | 7:41PM1.48m | |||||||
Low Tide | 10:08PM1.08m | 10:31AM0.14m | 10:48PM0.99m | 11:12AM0.14m | 11:25PM0.88m | 11:48AM0.17m | 00:00AM0.78m | 12:23PM0.24m | 00:35AM0.68m | 12:57PM0.34m | 1:12AM0.59m | 1:28PM0.46m | 1:51AM0.52m | ||||||
 |  | |  |  | |  | | | | | |  | | | | | | | |
 | — | 4:58 | — | — | 4:58 | — | — | 4:58 | — | — | 5:00 | — | — | 5:01 | — | — | 5:01 | — | — |
 | 6:36 | — | 6:35 | — | — | 6:34 | — | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:29 | — |
mm | 51 | 10 | 13 | 1 | — | 4 | 9 | 1 | 4 | 17 | 3 | 4 | — | — | — | — | — | — | — |
Temp °C | 25 | 26 | 26 | 24 | 27 | 28 | 26 | 28 | 29 | 27 | 27 | 28 | 26 | 27 | 28 | 25 | 25 | 26 | 25 |
Feels °C | 23 | 26 | 27 | 24 | 28 | 30 | 28 | 29 | 31 | 29 | 28 | 29 | 25 | 25 | 27 | 25 | 27 | 27 | 25 |
Swell 1 Height (m) Direction Period (s) | SE 13 | S 10 | SSW 10 | S 6 | SSW 10 | S 10 | SSW 9 | SSW 9 | SSW 9 | SE 9 | S 11 | S 10 | S 9 | SSW 9 | SSW 9 | SSW 9 | SSW 10 | SSW 9 | SSW 9 |
| kJ | 6 | 130 | 59 | 11 | 38 | 47 | 28 | 28 | 28 | 20 | 61 | 51 | 41 | 27 | 28 | 28 | 31 | 16 | 15 |
Swell 2 Height (m) Direction Period (s) | E 11 | SE 13 | SE 12 | SSW 10 | S 5 | E 10 | S 12 | SSE 11 | S 9 | S 12 | SE 8 | SE 8 | ESE 10 | ESE 10 | ESE 11 | ESE 10 | ESE 10 | SE 11 | SE 10 |
| kJ | 2 | 6 | 6 | 39 | 5 | 2 | 11 | 12 | 6 | 45 | 17 | 21 | 10 | 10 | 22 | 20 | 10 | 5 | 4 |
Swell 3 Height (m) Direction Period (s) | SSE 13 | SE 10 | E 10 | ESE 5 | SE 11 | SE 12 | SE 11 | ESE 10 | SE 10 | SSW 9 | SE 11 | E 11 | SE 10 | SSE 12 | SSE 12 | SSE 11 | SE 11 | SE 6 | S 8 |
| kJ | 16 | 4 | 2 | 5 | 5 | 5 | 5 | 10 | 4 | 15 | 4 | 2 | 4 | 13 | 13 | 12 | 5 | 1 | 1 |
Wind waves Height (m) Direction Period (s) | SSW 5 | ESE 3 | SE 5 | — | NNE 2 | — | — | NE 3 | — | — | ENE 2 | — | NE 2 | NNE 3 | — | — | — | — | S 3 |
| kJ | 91 | 4 | 11 | — | 1 | — | — | 2 | — | — | 1 | — | 1 | 3 | — | — | — | — | 1 |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 142 | 27 | 0 | 0 | 38 | 0 | 38 | 0 | 38 | 0 | 0 | 0 | 0 | 0 | 38 | 2 | 38 | 64 | 54 |
Best forecast wave conditions in Kanagawa | |||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||
Header Global | |||||||||||||||||||
- Map Icons:
Break
Live Wave Height (m)
Live Wind Speed (km/h)
Surf Rating (10 Max)
Ocean Swells (m)- Wind Speed (km/h)
Latest Updates
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 Rock Island 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 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.
Nearest