Surf Forecasts:
Rock Island surf forecast from 1 Sep 2026:
- Best quality surf: Tuesday 8 Sep, 3PM (local time) - 8ft (2.5m), 11s period, SSE swell with offshore winds.
- Most powerful swell: Tuesday 8 Sep, 9PM (local time) - 10ft (3.0m), 12s period, SSE swell with 2,587 kJ wave energy.
- Next surfable swell (1★+): Thursday 3 Sep, 9PM (local time) - 1ft (0.3m), 12s 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 Thursday (Sep 03) at 9PM. The primary swell is predicted to be 0.3m and 12s period with a secondary swell of 0.4m and 8s. Another secondary swell of 0.4m and 6s is also forecast. Another secondary swell of 0.3m and 2s 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 3.0m 12s and forecast to arrive on Tuesday (Sep 08) at 9PM. Winds are predicted to be 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 Monday (Sep 07) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Thu 3rd Sep) | 1ft (0.3m) 12s |
| Best Surf | 3PM (Tue 8th Sep) | 8ft (2.5m) 11s |
| Most Powerful | 9PM (Tue 8th Sep) | 10ft (3.0m) 12s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright, Rusty here, lookin’ at the Rock Island forecast for the next couple weeks.
Let’s be real – the first few days are a bust. From Wednesday, September 2nd through Sunday, September 6th, the surf is tiny, weak, and the wind is mostly junk. The swell is barely 0.3 to 0.6 feet, and the energy is low. Water temp is about normal for this time of year. Not worth paddling out.
Then Monday, September 7th, things start to turn. The morning is still meh with a 0.7 feet SSE swell, period 10 seconds, and moderate energy. But the afternoon shows a real pulse: 2 feet from the S, period 13 seconds, energy jumping to 766. The wind goes light offshore, cleaning it up. That’s the first real surfable window.
Tuesday, September 8th, is a tale of two halves. Morning is blown out by a strong cross-onshore, but the afternoon is a standout. The swell hits 3 feet from the SSE, period 11 seconds, with strong energy at 1616. A light offshore breeze makes it clean and powerful. This is for the experienced crew only – beginners, stay out.
Wednesday, September 9th, is the gem. The swell is 3 feet from the SSE, period 10-11 seconds, and the energy is strong to very strong (2006 to 3121). Offshore wind all day, moderate in the morning, gentle in the afternoon. This is big, clean, and perfect for experts. Over 3 feet means serious power.
After that, it gets messy again. Thursday, September 10th, has a near gale cross-onshore wrecking a 3-foot swell. The rest of the week into the weekend is onshore winds and lumpy conditions, with the swell dropping to 1-2 feet. There’s a small window Sunday, September 13th, with a fresh offshore and a 1.0-foot S swell, period 12 seconds, but it’s only marginal.
The second week is spotty. Tuesday, September 15th, has a 2-foot swell with a 14-second period and strong energy (1584), but the wind is cross-onshore, making it choppy. The final day, Thursday, September 17th, has a fresh offshore and a 1-foot S swell, 12-second period, moderate energy (504) – surfable, but nothing special.
If you’re picking your moments, it’s the afternoon of Tuesday, September 8th, and all of Wednesday, September 9th. That’s the real deal for the big-wave surfers. The rest? You’re waiting on the wind.
Rusty.
Short Range ForecastHeavy rain (total 118mm), heaviest during Fri morning. Warm (max 27°C on Wed morning, min 20°C on Fri afternoon). Winds increasing (light winds from the ESE on Tue night, fresh winds from the N by Fri morning). | Days 5-7 Weather SummaryHeavy rain (total 277mm), heaviest during Sun afternoon. Warm (max 25°C on Mon afternoon, min 18°C on Sat morning). Winds decreasing (near gales from the N on Sun night, light winds from the NNE by Mon afternoon). | ||||||||||||||||||
Wednesday 2 | Thursday 3 | Friday 4 | Saturday 5 | Sunday 6 | Monday 7 | ||||||||||||||
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 8 | SSW 8 | SSW 8 | SSW 9 | S 9 | S 9 | S 11 | S 10 | SSW 10 | SSW 9 | SSW 9 | S 9 | SSW 8 | SE 7 | SE 7 | SE 8 | SSE 10 | S 13 | S 12 |
Wave Graph  | |||||||||||||||||||
 kJ | 14 | 14 | 24 | 25 | 39 | 38 | 62 | 73 | 75 | 113 | 64 | 55 | 24 | 12 | 14 | 17 | 98 | 736 | 722 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-on | on | cross-on | on | on | off | off | off | off | off | off | off | off | off | cross-off | off | off | cross |
High Tide | 8:22AM1.41m | 7:51PM1.49m | 9:19AM1.31m | 8:17PM1.47m | 10:36AM1.22m | 8:48PM1.44m | 12:35PM1.19m | 9:29PM1.40m | 2:50PM1.24m | 10:39PM1.34m | 3:40PM1.32m | 00:30AM1.32m | |||||||
Low Tide | 1:56AM0.40m | 1:58PM0.77m | 2:40AM0.39m | 2:27PM0.91m | 3:32AM0.40m | 2:58PM1.03m | 4:36AM0.42m | 3:39PM1.14m | 5:57AM0.42m | 5:39PM1.22m | 7:20AM0.40m | 8:06PM1.18m | |||||||
 |  |  |  | |  |  |  | | | | | | | | |  | |  | |
 | — | 5:13 | — | — | 5:13 | — | — | 5:15 | — | — | 5:16 | — | — | 5:16 | — | — | 5:16 | — | — |
 | 6:09 | — | 6:07 | — | — | 6:07 | — | — | 6:05 | — | — | 6:04 | — | — | 6:02 | — | — | 6:00 | — |
mm | 1 | — | — | — | — | 1 | 36 | 63 | 17 | 12 | 21 | 29 | 51 | 27 | 48 | 61 | 5 | 23 | 30 |
Temp °C | 26 | 27 | 27 | 26 | 27 | 27 | 26 | 21 | 21 | 21 | 19 | 19 | 19 | 19 | 19 | 21 | 22 | 25 | 27 |
Feels °C | 28 | 30 | 29 | 28 | 30 | 29 | 28 | 20 | 19 | 20 | 15 | 15 | 15 | 15 | 13 | 18 | 22 | 26 | 28 |
Swell 1 Height (m) Direction Period (s) | SSW 8 | SSW 8 | SSW 8 | SSW 9 | S 9 | S 9 | S 11 | S 10 | SSW 10 | SSW 9 | SSW 9 | S 9 | SE 7 | SE 7 | SE 7 | SE 8 | SSE 10 | S 13 | S 12 |
| kJ | 14 | 14 | 24 | 25 | 39 | 38 | 62 | 73 | 75 | 113 | 64 | 55 | 18 | 12 | 14 | 17 | 98 | 736 | 722 |
Swell 2 Height (m) Direction Period (s) | SE 10 | SE 10 | SE 10 | SSW 10 | SE 10 | SE 10 | SSE 6 | SE 6 | SE 8 | SE 8 | SE 8 | SE 8 | SSW 8 | SSE 8 | SSE 8 | SSE 7 | S 16 | ESE 7 | ESE 10 |
| kJ | 4 | 4 | 4 | 10 | 4 | 4 | 16 | 11 | 21 | 15 | 9 | 9 | 24 | 6 | 6 | 5 | 20 | 18 | 20 |
Swell 3 Height (m) Direction Period (s) | E 11 | SE 4 | E 10 | SE 11 | E 10 | S 13 | SE 10 | SSE 9 | E 9 | SE 12 | — | E 13 | — | SSW 8 | SW 9 | SW 9 | SE 11 | ESE 11 | — |
| kJ | 2 | 1 | 2 | 4 | 2 | 3 | 4 | 8 | 6 | 6 | — | 3 | — | 7 | 3 | 3 | 5 | 12 | — |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | S 2 | — | — | — | — | — | — | ENE 2 | NNE 3 | NNE 3 | N 3 | N 4 | N 4 | NNE 3 |
| kJ | — | — | — | — | — | 1 | — | — | — | — | — | — | 1 | 4 | 2 | 7 | 12 | 12 | 9 |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 38 | 16 | 18 | 38 | 18 | 76 | 0 | 38 | 86 | 0 | 565 | 565 | 487 | 552 | 552 | 55 | 0 | 0 | 510 |
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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