Surf Forecasts:
Rock Island surf forecast from 8 Sep 2026:
- Best quality surf: Thursday 10 Sep, 3PM (local time) - 2.5ft (0.8m), 8s period, S swell with offshore winds.
- Most powerful swell: Wednesday 9 Sep, 6PM (local time) - 8ft (2.5m), 9s period, SSW swell with 1,070 kJ wave energy.
- Next surfable swell (1★+): Thursday 10 Sep, 3PM (local time) - 2.5ft (0.8m), 8s 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 Thursday (Sep 10) at 3PM. The primary swell is predicted to be 0.8m and 8s period with a secondary swell of 0.3m and 9s. 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 2.5m 9s and forecast to arrive on Wednesday (Sep 09) at 6PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.7m 3s period and expected on Thursday (Sep 10) at 12AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Thu 10th Sep) | 2.5ft (0.8m) 8s |
| Best Surf | 3PM (Thu 10th Sep) | 2.5ft (0.8m) 8s |
| Most Powerful | 6PM (Wed 9th Sep) | 8ft (2.5m) 9s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let's get into what’s happening at Rock Island.
Honestly, the first week and a half is a total bust. There's a long dry spell from Wednesday the 9th all the way through to the weekend of the 21st of September. It's mostly tiny, weak, and messy. You'll see a few mornings with clean offshore wind out of the NNE, but the swell is barely a ripple, sitting around 1ft to 3ft. The water is sitting at 83°, which is a touch warmer than usual for this time of year, so it's not all bad if you just want a float.
Alright, things finally start looking up on Monday the 21st of September. A new SSW groundswell shows up. The morning session is worth paddling out for, with a clean 3ft swell from the South at a solid 13 seconds, and glassy conditions with barely a breath of wind. The combined energy is moderate, so it’ll have some push. It's a reef, so that long period should wrap in pretty nicely.
Tuesday the 22nd of September is where the real magic starts. The afternoon is the absolute highlight. We’re looking at a clean 3ft swell from the South, but with a super long period of 15 seconds and strong energy. The wind goes glassy. Get your log or a mid-length out, it’s going to be smooth as silk.
Wednesday the 23rd of September is another cracker. The morning brings a 4-5ft SSW swell with a 15-second period and very strong energy. With a light offshore breeze from the North, it’s going to be clean and powerful. The afternoon goes glassy again, dropping a touch to 3-4ft from the SSW, but the period stays long and the energy is still pumping. This is the kind of day you plan your week around.
Then we get to Thursday the 24th of September, and you need to be careful. The swell hits 5-6ft in the morning and builds to 6ft+ in the afternoon from the SSW, with a massive 16-second period. The energy is through the roof. With offshore wind from the NE, it will look perfect, but anything over 5ft on a shallow reef like Rock Island is expert territory. That long period is going to make it bowl up and get heavy. If you're not solid, sit this one out and watch the show.
So here’s the plan: ignore the first ten days. Your window is Monday the 21st to Thursday the 24th of September. The best bets are Tuesday afternoon and Wednesday morning. That’s where you’ll find the cleanest conditions and the best shaped waves. Just respect that Thursday, it’s got some serious muscle.
Stay stoked.
Rusty.
Short Range ForecastHeavy rain (total 41mm), heaviest during Wed night. Warm (max 29°C on Wed afternoon, min 19°C on Thu afternoon). Winds decreasing (fresh winds from the SW on Wed morning, light winds from the NNE by Fri morning). | Days 4-6 Weather SummaryMostly dry. Warm (max 26°C on Sun afternoon, min 21°C on Sat morning). Mainly fresh winds. | ||||||||||||||||||||
Wednesday 9 | Thursday 10 | Friday 11 | Saturday 12 | Sunday 13 | Monday 14 | Tuesday 15 | |||||||||||||||
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 8 | S 9 | S 9 | S 8 | S 8 | S 8 | S 8 | S 8 | S 8 | SSW 7 | SSW 7 | SSW 7 | SE 9 | SE 9 | SE 8 | SE 9 | SE 9 | SE 8 | SSE 8 | SE 7 | SE 7 |
Wave Graph  | |||||||||||||||||||||
 kJ | 512 | 562 | 258 | 113 | 84 | 45 | 28 | 29 | 29 | 18 | 10 | 9 | 13 | 12 | 17 | 21 | 27 | 23 | 22 | 12 | 12 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | off | off | off | off | off | off | off | off | cross-off | off | off | off | glassy | on | on | on | glassy | on | cross |
High Tide | 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 | 6:24AM1.58m | 6:25PM1.51m | 7:08AM1.53m | 6:48PM1.52m | ||||||||
Low Tide | 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 | 12:29PM0.55m | 00:43AM0.37m | 12:59PM0.67m | 1:21AM0.32m | |||||||
 |  |  |  |  |  | | |  |  | |  |  | |  | | |  | | |  | |
 | 5:18 | — | — | 5:20 | — | — | 5:20 | — | — | 5:20 | — | — | 5:22 | — | — | 5:22 | — | — | 5:22 | — | — |
 | — | 5:58 | — | — | 5:57 | — | — | 5:55 | — | — | 5:53 | — | — | 5:52 | — | — | 5:51 | — | — | 5:50 | — |
mm | — | 3 | 11 | 1 | 11 | 8 | 1 | 5 | 1 | — | — | — | — | — | — | — | — | — | — | — | 1 |
Temp °C | 28 | 29 | 22 | 20 | 20 | 20 | 20 | 20 | 21 | 22 | 23 | 23 | 23 | 26 | 25 | 26 | 26 | 25 | 26 | 26 | 25 |
Feels °C | 27 | 31 | 20 | 17 | 19 | 19 | 20 | 20 | 21 | 22 | 24 | 24 | 24 | 30 | 29 | 24 | 25 | 24 | 28 | 28 | 27 |
Swell 1 Height (m) Direction Period (s) | ESE 10 | SSE 8 | S 9 | S 8 | S 8 | S 8 | S 8 | S 8 | S 8 | SSW 7 | SSW 7 | SSW 7 | SE 9 | SE 9 | SE 8 | SE 9 | SE 9 | SE 8 | SSE 8 | SE 7 | S 4 |
| kJ | 10 | 174 | 258 | 113 | 84 | 45 | 28 | 29 | 29 | 18 | 10 | 9 | 13 | 12 | 17 | 21 | 27 | 23 | 22 | 12 | 4 |
Swell 2 Height (m) Direction Period (s) | SE 12 | ESE 10 | SE 9 | E 11 | SE 9 | SE 9 | SE 9 | SE 10 | SE 10 | SE 10 | SE 10 | SE 9 | SSW 7 | SSW 7 | S 7 | SW 8 | E 12 | S 7 | S 7 | E 12 | SE 7 |
| kJ | 6 | 10 | 3 | 2 | 14 | 3 | 3 | 4 | 4 | 4 | 4 | 3 | 5 | 5 | 1 | 2 | 12 | 1 | 1 | 3 | 12 |
Swell 3 Height (m) Direction Period (s) | E 17 | E 16 | SE 11 | — | E 15 | E 16 | SE 10 | S 8 | E 14 | S 8 | E 14 | — | E 13 | E 13 | S 8 | E 12 | E 15 | SW 7 | E 16 | — | SE 9 |
| kJ | 6 | 5 | 5 | — | 17 | 5 | 4 | 1 | 4 | 1 | 4 | — | 3 | 3 | 1 | 3 | 4 | 2 | 5 | — | 3 |
Wind waves Height (m) Direction Period (s) | S 8 | S 9 | NNE 3 | NE 3 | NNE 3 | NNE 3 | NNE 2 | NNE 2 | NE 3 | NE 2 | NNE 2 | — | NNE 2 | — | — | — | S 4 | SSW 3 | — | — | SSW 3 |
| kJ | 512 | 562 | 10 | 6 | 4 | 2 | 1 | 1 | 1 | 1 | 1 | — | 1 | — | — | — | 9 | 4 | — | — | 5 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 491 | 122 | 142 | 8 | 0 | 0 | 51 | 51 | 38 | 51 | 51 | 51 | 51 | 16 | 16 | 92 | 90 | 38 | 16 | 77 | 16 |
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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