Surf Forecasts:
Rock Island surf forecast from 4 Sep 2026:
- Best quality surf: Monday 7 Sep, 3PM (local time) - 13ft (4.0m), 11s period, S swell with glassy winds.
- Most powerful swell: Monday 7 Sep, 3PM (local time) - 13ft (4.0m), 11s period, S swell with 3,459 kJ wave energy.
- Next surfable swell (1★+): Monday 7 Sep, 3PM (local time) - 13ft (4.0m), 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 Monday (Sep 07) at 3PM. The primary swell is predicted to be 4.0m and 11s period with a secondary swell of 2.5m 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 4.0m 11s and forecast to arrive on Monday (Sep 07) at 3PM. Winds are predicted to be glassy at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.9m 4s period and expected on Sunday (Sep 06) at 6PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Mon 7th Sep) | 13ft (4.0m) 11s |
| Best Surf | 3PM (Mon 7th Sep) | 13ft (4.0m) 11s |
| Most Powerful | 3PM (Mon 7th Sep) | 13ft (4.0m) 11s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s have a look at what’s on the cards for Rock Island over the next couple of weeks. I’ve got to be straight with you, it’s a pretty lean run for most of it, but there’s one afternoon that’s going to make it all worth it if you’re an experienced surfer.
The first hint of anything worth paddling out for doesn’t show up until Monday, September 7th. That morning is a write-off with a strong, gusty cross-off wind and heavy rain making a messy 8ft swell – steer clear. But then, Monday afternoon rolls around and the whole picture flips. The wind dies right off to glassy, and a solid 13ft S swell rolls in with a period of 11 seconds. The combined energy is a massive 4709, which is serious power. This is a reef break, so that long-period groundswell will be holding up nicely in the lineup, but I’m telling you now: this is for experts only. Anything over 8ft like this is no place for beginners, and with crowds possible here, you want to be on your game. The water feels about average for this time of year.
Tuesday, September 8th morning, the swell drops a bit to 6ft from the S (combined energy 681), with a moderate offshore breeze cleaning it up. It’s decent, but it’s a step down from the Monday afternoon peak. That morning is worth a look if you missed the bigger stuff.
After that, things slim down fast. The rest of the week into the weekend has a few surfable moments – for example, Wednesday morning, September 9th, with 4ft S swell and glassy conditions (combined energy 245) – but the quality drops off quickly. The swell gets smaller and the wind becomes less reliable.
From Friday, September 12th right through to the end of the forecast on Sunday, September 20th, it’s a long stretch of tiny waves. Most days see swell under 2ft with combined energy barely scraping 50, and the direction is coming from the SSE or SSW with short periods of 4 to 9 seconds. Some mornings are glassy, but the waves just aren’t there to ride. It’s a proper empty run for nearly nine days.
Best on offer: Monday afternoon, September 7th, at Rock Island. That’s the standout. Get it while it’s big, clean, and glassy.
Stay safe out there.
Rusty.
Short Range ForecastHeavy rain (total 371mm), heaviest during Sun night. Warm (max 25°C on Fri night, min 21°C on Fri night). Mainly near gales. | Days 5-7 Weather SummaryHeavy rain (total 42mm), heaviest during Mon night. Warm (max 25°C on Wed afternoon, min 19°C on Thu afternoon). Winds increasing (calm on Mon night, fresh winds from the N by Thu afternoon). | ||||||||||||||||||
Saturday 5 | Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | ||||||||||||||
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 9 | SSW 9 | SSW 9 | SSW 8 | SSE 8 | ESE 8 | S 12 | S 10 | S 11 | SSE 11 | S 11 | S 10 | S 10 | S 9 | S 9 | S 9 | S 10 | S 9 | S 9 |
Wave Graph  | |||||||||||||||||||
 kJ | 49 | 50 | 27 | 14 | 7 | 7 | 134 | 1019 | 3459 | 1230 | 657 | 551 | 441 | 239 | 270 | 287 | 220 | 164 | 96 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | cross-off | off | off | off | off | off | cross-off | glassy | glassy | off | cross-off | off | glassy | cross-on | off | off | cross-off | cross-off |
High Tide | 12:35PM1.19m | 9:29PM1.40m | 2:50PM1.24m | 10:39PM1.34m | 3:40PM1.32m | 00:30AM1.32m | 4:09PM1.37m | 2:05AM1.36m | 4:34PM1.41m | 3:13AM1.43m | 4:57PM1.44m | ||||||||
Low Tide | 4:36AM0.42m | 3:39PM1.14m | 5:57AM0.42m | 5:39PM1.22m | 7:20AM0.40m | 8:06PM1.18m | 8:30AM0.36m | 9:11PM1.08m | 9:25AM0.32m | 9:53PM0.96m | 10:09AM0.31m | 10:28PM0.82m | |||||||
 |  |  |  | |  | |  | | | | |  |  | |  | | |  | |
 | — | 5:16 | — | — | 5:16 | — | — | 5:16 | — | — | 5:18 | — | — | 5:18 | — | — | 5:20 | — | — |
 | 6:05 | — | 6:04 | — | — | 6:02 | — | — | 6:00 | — | — | 6:00 | — | — | 5:58 | — | — | 5:57 | — |
mm | 39 | 5 | — | — | — | 9 | 192 | 97 | 29 | 11 | 3 | 5 | 9 | 2 | 4 | 3 | 3 | 2 | — |
Temp °C | 25 | 22 | 22 | 22 | 23 | 22 | 24 | 24 | 24 | 24 | 24 | 23 | 23 | 24 | 25 | 23 | 21 | 19 | 21 |
Feels °C | 25 | 21 | 21 | 20 | 19 | 17 | 22 | 18 | 28 | 26 | 25 | 24 | 25 | 28 | 29 | 25 | 19 | 15 | 20 |
Swell 1 Height (m) Direction Period (s) | SSW 9 | SSW 9 | SSW 9 | SSW 8 | SSE 8 | ESE 8 | S 12 | SSE 10 | SSE 10 | SSE 11 | S 11 | S 10 | S 10 | S 9 | S 9 | S 9 | S 10 | S 9 | S 9 |
| kJ | 49 | 50 | 27 | 14 | 7 | 7 | 134 | 787 | 1250 | 1230 | 657 | 551 | 441 | 239 | 270 | 287 | 220 | 164 | 96 |
Swell 2 Height (m) Direction Period (s) | SSE 6 | SE 8 | ESE 7 | SE 8 | SSW 8 | SSE 8 | SSE 7 | — | — | E 9 | SSW 11 | SSW 11 | SSW 10 | E 12 | SSE 8 | SE 11 | ESE 11 | ESE 11 | E 16 |
| kJ | 4 | 11 | 4 | 11 | 7 | 6 | 37 | — | — | 41 | 24 | 73 | 307 | 3 | 175 | 5 | 11 | 11 | 5 |
Swell 3 Height (m) Direction Period (s) | SE 9 | SE 9 | E 3 | SW 10 | SE 7 | S 8 | SE 8 | — | — | — | — | — | E 10 | E 12 | E 16 | E 16 | E 15 | E 7 | ESE 10 |
| kJ | 3 | 12 | 1 | 4 | 2 | 1 | 17 | — | — | — | — | — | 2 | 3 | 5 | 5 | 4 | 4 | 10 |
Wind waves Height (m) Direction Period (s) | NE 3 | E 4 | — | NE 3 | NNE 4 | NNE 4 | NE 4 | S 10 | S 11 | — | NE 3 | NE 2 | NNE 3 | NNE 3 | NNE 3 | NE 2 | NE 3 | N 3 | N 3 |
| kJ | 2 | 3 | — | 4 | 18 | 16 | 12 | 1019 | 3459 | — | 2 | 1 | 1 | 1 | 2 | 1 | 5 | 5 | 3 |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 0 | 12 | 38 | 487 | 487 | 552 | 509 | 27 | 0 | 0 | 0 | 12 | 0 | 0 | 7 | 0 | 38 | 29 | 2 |
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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