Surf Forecasts:
Rock Island surf forecast from 6 Sep 2026:
- Best quality surf: Tuesday 8 Sep, 9AM (local time) - 4.5ft (1.4m), 9s period, S swell with glassy winds.
- Most powerful swell: Monday 7 Sep, 12PM (local time) - 10ft (3.0m), 9s period, S swell with 1,320 kJ wave energy.
- Next surfable swell (1★+): Tuesday 8 Sep, 9AM (local time) - 4.5ft (1.4m), 9s 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 Tuesday (Sep 08) at 9AM. The primary swell is predicted to be 1.4m and 9s period with a secondary swell of 1.1m and 9s. 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 3.0m 9s and forecast to arrive on Monday (Sep 07) 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 0.5m 3s period and expected on Wednesday (Sep 09) at 6PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Tue 8th Sep) | 4.5ft (1.4m) 9s |
| Best Surf | 9AM (Tue 8th Sep) | 4.5ft (1.4m) 9s |
| Most Powerful | 12PM (Mon 7th Sep) | 10ft (3.0m) 9s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright, Rusty here again, looking at the same 16 days for Rock Island. This is a reef break, good for beginners, exposed to south swells. Water temp is a touch warmer than usual for the season, sitting at 83°F.
Man, this is a tough outlook. The first few days are a total waste. Monday the 7th is a mess with heavy rain, strong cross-on wind, and a huge, unruly 10ft swell. The wave energy is off the charts (2076), but it’s not surfable. Tuesday the 8th is the only real bright spot. Tuesday morning, the wind goes glassy from the north, and we get a clean 5ft south swell with moderate energy (527). It’s the only time the report says "very good," and that glassy surface will be butter. The swell period is short at 9 seconds, so not a deep-water groundswell, but for a beginner reef, it’s a fun, clean session. Crowds can show up sometimes, so expect a few others.
After that, it’s a long, flat spell. From Wednesday the 9th through the 22nd, it’s mostly poor. The swell drops to tiny numbers, wind gets messy, or the energy evaporates to two-digit numbers like 14 or 16. Thursday the 10th has some offshore breeze, but the swell is under 3ft and weak (115 energy). It’s surfable, but nothing special.
The very end of the run, around Monday the 21st and Tuesday the 22nd, shows a pulse. The swell period jumps to 18-19 seconds—that’s a very long, powerful groundswell. It’ll wrap nicely into this reef. The swell height is still small (2ft to 4ft), but the energy climbs back into the moderate range (340 to 764), and the wind stays clean or offshore. It’s rated as "marginal" and only a 1 or 2 out of 10, so it’s not a classic, but it’s something. The long period means long waits between sets, but it’ll be easier to paddle out.
So, your one and only real shot is Tuesday morning, the 8th. The rest of the 16 days is a long stretch of flat or ugly conditions. For a spot that’s usually fairly consistent, this is a bummer, but it’s just how it goes sometimes. Forecasts can always change.
Rusty.
Short Range ForecastHeavy rain (total 65mm), heaviest during Mon morning. Warm (max 28°C on Wed morning, min 21°C on Wed night). Winds increasing (calm on Tue morning, fresh winds from the N by Wed night). | Days 4-6 Weather SummaryHeavy rain (total 35mm), heaviest during Fri morning. Warm (max 23°C on Sat afternoon, min 20°C on Thu night). Wind will be generally light. | ||||||||||||||||||||
Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | Friday 11 | Saturday 12 | Sunday 13 | |||||||||||||||
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 9 | S 9 | S 9 | S 9 | SSE 9 | SSW 10 | SSW 10 | S 9 | S 9 | S 8 | S 8 | S 8 | S 8 | S 8 | S 7 | S 7 | S 7 | SSW 7 | SE 9 | SE 7 | SE 8 |
Wave Graph  | |||||||||||||||||||||
 kJ | 739 | 1288 | 476 | 320 | 276 | 506 | 351 | 621 | 313 | 113 | 65 | 30 | 28 | 29 | 17 | 9 | 8 | 5 | 12 | 14 | 35 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | cross-on | glassy | on | on | on | on | off | off | off | off | off | off | off | off | off | off | off | on | on |
High Tide | 3:40PM1.32m | 00:30AM1.32m | 4:09PM1.37m | 2:05AM1.36m | 4:34PM1.41m | 3:13AM1.43m | 4:57PM1.44m | 4:08AM1.50m | 5:19PM1.47m | 4:56AM1.56m | 5:41PM1.48m | 5:41AM1.58m | 6:03PM1.50m | ||||||||
Low Tide | 8:06PM1.18m | 8:30AM0.36m | 9:11PM1.08m | 9:25AM0.32m | 9:53PM0.96m | 10:09AM0.31m | 10:28PM0.82m | 10:49AM0.32m | 11:01PM0.69m | 11:24AM0.37m | 11:34PM0.56m | 11:58AM0.45m | 00:08AM0.45m | ||||||||
 |  |  |  | |  | | |  |  |  |  |  | |  | | | |  | |  | |
 | 5:16 | — | — | 5:18 | — | — | 5:18 | — | — | 5:20 | — | — | 5:20 | — | — | 5:20 | — | — | 5:22 | — | — |
 | — | 6:00 | — | — | 6:00 | — | — | 5:58 | — | — | 5:57 | — | — | 5:55 | — | — | 5:53 | — | — | 5:52 | — |
mm | 23 | 5 | 5 | — | 9 | 4 | 1 | 9 | 9 | — | 3 | 12 | 19 | 1 | — | — | — | — | — | — | — |
Temp °C | 25 | 26 | 26 | 26 | 27 | 26 | 28 | 27 | 21 | 21 | 22 | 21 | 20 | 21 | 22 | 22 | 23 | 23 | 26 | 27 | 26 |
Feels °C | 26 | 28 | 30 | 31 | 31 | 28 | 30 | 29 | 18 | 20 | 21 | 21 | 21 | 23 | 24 | 23 | 24 | 25 | 30 | 29 | 29 |
Swell 1 Height (m) Direction Period (s) | — | S 9 | S 9 | S 9 | S 9 | SSW 9 | SSE 8 | E 12 | S 9 | S 8 | S 8 | S 8 | S 8 | S 8 | S 7 | S 7 | S 7 | SSW 7 | SE 9 | SE 7 | SE 8 |
| kJ | — | 788 | 476 | 320 | 165 | 185 | 94 | 3 | 313 | 113 | 65 | 30 | 28 | 29 | 17 | 9 | 8 | 5 | 12 | 14 | 35 |
Swell 2 Height (m) Direction Period (s) | — | — | ESE 10 | SSW 9 | SSW 9 | SSE 8 | E 12 | E 16 | E 16 | E 11 | E 11 | SE 9 | SE 9 | SE 10 | SE 9 | SE 10 | SE 10 | SE 7 | SSW 7 | SE 9 | SSW 12 |
| kJ | — | — | 10 | 197 | 90 | 76 | 3 | 5 | 5 | 2 | 2 | 3 | 3 | 4 | 3 | 4 | 4 | 2 | 5 | 3 | 14 |
Swell 3 Height (m) Direction Period (s) | — | — | — | ESE 10 | ESE 10 | ESE 10 | SE 12 | — | E 16 | — | E 15 | E 16 | S 9 | S 8 | S 8 | S 8 | E 14 | SE 9 | E 13 | S 7 | S 7 |
| kJ | — | — | — | 10 | 10 | 10 | 6 | — | 5 | — | 17 | 5 | 1 | 1 | 1 | 1 | 4 | 3 | 3 | 4 | 1 |
Wind waves Height (m) Direction Period (s) | S 9 | S 9 | — | — | SSE 9 | SSW 10 | SSW 10 | S 9 | NNE 3 | NE 2 | NE 3 | NNE 3 | NNE 3 | — | — | — | — | — | — | — | — |
| kJ | 739 | 1288 | — | — | 276 | 506 | 351 | 621 | 1 | 2 | 2 | 3 | 1 | — | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 10 | 14 | 12 | 0 | 14 | 14 | 488 | 14 | 38 | 0 | 0 | 38 | 54 | 16 | 51 | 51 | 51 | 16 | 16 | 18 | 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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