Surf Forecasts:
Rock Island surf forecast from 8 Aug 2026:
- Best quality surf: Sunday 9 Aug, 6AM (local time) - 2.5ft (0.7m), 11s period, S swell with glassy winds.
- Most powerful swell: Saturday 8 Aug, 12PM (local time) - 3.5ft (1.1m), 11s period, S swell with 297 kJ wave energy.
- Next surfable swell (1★+): Sunday 9 Aug, 6AM (local time) - 2.5ft (0.7m), 11s period with S 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 Sunday (Aug 09) at 6AM. The primary swell is predicted to be 0.7m and 11s period with a secondary swell of 0.4m and 10s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Rock Island in the next 16 days are 1.1m 11s and forecast to arrive on Saturday (Aug 08) at 12PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.6m 3s period and expected on Friday (Aug 14) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Sun 9th Aug) | 2.5ft (0.7m) 11s |
| Best Surf | 6AM (Sun 9th Aug) | 2.5ft (0.7m) 11s |
| Most Powerful | 12PM (Sat 8th Aug) | 3.5ft (1.1m) 11s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright folks, Rusty here again, breakin’ down the same stretch for Rock Island. This reef break is a mellow wave for beginners, exposed to the south.
Gotta level with you – the first week and a half is a snoozer. From now until about the 19th of August, the swell is puny, runnin’ mostly 1 to 2 feet, with a mix of onshore and cross-off winds. There’s a glimmer Sunday morning the 9th with a 2-foot SSW swell and glassy conditions, but the energy is weak (151), and the waves are just “ordinary.” The rest of that week is a bust – barely any push, and the wind is messin’ with the surface.
Now, here’s the one to circle. Thursday, the 20th of August, the morning is your golden ticket. A clean 4.5-foot south swell, 10-second period, and flat calm – glassy as it gets. The combined energy jumps to 400, a solid moderate punch, and the forecast says “expect good surf conditions.” Rock Island will be clean, rideable, and fun. The afternoon of the same day hits 5 feet, but the wind turns onshore from the SSW, so get out there early.
After that, it fades back to small, messy conditions. The 23rd shows a 13-second period from the southeast, but it’s only 1.3 feet, and the energy is low at 133. The offshore wind will keep it clean, but there’s just not enough wave.
So, if you’re itching for a session, the 20th of August morning is the standout. The rest is a waiting game. Hang in there.
Short Range ForecastSome drizzle, heaviest during Mon night. Warm (max 29°C on Sun afternoon, min 23°C on Mon night). Wind will be generally light. | Days 4-6 Weather SummaryHeavy rain (total 30mm), heaviest during Wed night. Warm (max 29°C on Wed afternoon, min 24°C on Wed night). Winds decreasing (fresh winds from the S on Tue night, calm by Wed night). | ||||||||||||||||||||
Saturday 8 | Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | Thursday 13 | Friday 14 | |||||||||||||||
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) | S 11 | S 11 | SSW 11 | SSW 10 | SSW 11 | S 10 | S 12 | SSW 11 | S 10 | SSW 10 | SSW 11 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 9 | SSW 9 | SSW 9 |
Wave Graph  | |||||||||||||||||||||
 kJ | 307 | 284 | 191 | 112 | 88 | 75 | 69 | 66 | 74 | 63 | 66 | 60 | 60 | 63 | 85 | 58 | 39 | 38 | 29 | 29 | 28 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | cross-on | glassy | on | cross-off | cross-off | glassy | cross-off | on | on | on | cross-off | cross-on | glassy | off | cross-off | off | off | cross-off | off |
High Tide | 2:57PM1.19m | 11:28PM1.38m | 4:09PM1.28m | 00:45AM1.38m | 4:47PM1.36m | 2:03AM1.40m | 5:17PM1.41m | 3:09AM1.45m | 5:43PM1.45m | 4:05AM1.50m | 6:08PM1.47m | 4:55AM1.54m | 6:31PM1.48m | ||||||||
Low Tide | 5:47PM1.15m | 7:52AM0.33m | 7:53PM1.19m | 8:54AM0.25m | 9:16PM1.16m | 9:46AM0.18m | 10:08PM1.08m | 10:31AM0.14m | 10:48PM0.99m | 11:12AM0.14m | 11:25PM0.88m | 11:48AM0.17m | 00:00AM0.78m | ||||||||
 | |  | | | | |  |  | | | |  | |  | | | | | | | |
 | 4:54 | — | — | 4:54 | — | — | 4:56 | — | — | 4:56 | — | — | 4:58 | — | — | 4:58 | — | — | 4:58 | — | — |
 | — | 6:38 | — | — | 6:37 | — | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — | — | 6:34 | — | — | 6:31 | — |
mm | — | — | — | — | — | — | — | — | 1 | — | — | 4 | 2 | 2 | 12 | — | 4 | 6 | 1 | 6 | 17 |
Temp °C | 28 | 28 | 27 | 28 | 29 | 26 | 28 | 29 | 26 | 26 | 27 | 27 | 28 | 29 | 26 | 28 | 29 | 27 | 29 | 30 | 27 |
Feels °C | 30 | 29 | 29 | 31 | 29 | 27 | 29 | 32 | 27 | 24 | 27 | 25 | 29 | 30 | 28 | 28 | 30 | 29 | 29 | 31 | 28 |
Swell 1 Height (m) Direction Period (s) | S 11 | S 11 | SSW 11 | SSW 10 | SSW 11 | S 10 | S 12 | SSW 11 | S 10 | SSW 10 | SSW 11 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 9 | SSW 9 | SSW 9 |
| kJ | 307 | 284 | 191 | 112 | 88 | 75 | 69 | 66 | 74 | 63 | 66 | 60 | 60 | 63 | 85 | 58 | 39 | 38 | 29 | 29 | 28 |
Swell 2 Height (m) Direction Period (s) | ESE 11 | ESE 12 | ESE 12 | ESE 13 | ESE 13 | SW 12 | SW 11 | SW 11 | E 11 | SE 12 | SE 13 | S 4 | SSE 4 | SSE 4 | SE 10 | SE 12 | SE 9 | ESE 4 | SSE 11 | SE 6 | SE 6 |
| kJ | 11 | 13 | 28 | 34 | 34 | 23 | 20 | 20 | 9 | 5 | 6 | 9 | 1 | 2 | 4 | 5 | 3 | 2 | 12 | 6 | 5 |
Swell 3 Height (m) Direction Period (s) | SE 12 | SE 12 | ESE 15 | SE 12 | SE 12 | ESE 12 | ESE 12 | ESE 11 | SW 11 | E 10 | E 11 | SE 13 | SE 10 | SE 10 | SE 12 | SE 9 | SE 11 | SSE 11 | E 11 | SE 11 | SSE 10 |
| kJ | 6 | 6 | 21 | 5 | 5 | 14 | 14 | 13 | 5 | 2 | 2 | 6 | 4 | 4 | 5 | 3 | 5 | 12 | 2 | 5 | 10 |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | E 2 | — | S 3 | — | — | — | — | NNE 3 | ENE 3 | — | ENE 3 | NE 3 | ENE 3 |
| kJ | — | — | — | — | — | — | — | — | 1 | — | 2 | — | — | — | — | 3 | 1 | — | 7 | 2 | 1 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 18 | 54 | 14 | 0 | 54 | 0 | 0 | 0 | 0 | 76 | 136 | 38 | 0 | 64 | 0 | 0 | 38 | 0 | 38 | 64 | 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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