Surf Forecasts:
Rock Island surf forecast from 12 Sep 2026:
- Most powerful swell: Saturday 19 Sep, 9AM (local time) - 4.5ft (1.4m), 16s period, SE swell with 1,084 kJ wave energy.
Best Forecast Surf Conditions for Rock Island this week:
The most powerful waves expected at Rock Island in the next 16 days are 1.4m 16s and forecast to arrive on Saturday (Sep 19) at 9AM. Winds are predicted to be offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.8m 4s period and expected on Friday (Sep 18) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 9AM (Sat 19th Sep) | 4.5ft (1.4m) 16s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright folks, this is Rusty. Let's take a look at what's on the table.
We're in a bit of a waiting game here. For the first seven days, Rock Island is pretty much flat or just gutless with tiny windswell. The wind is often offshore but on waves that are barely a ripple. You’d be paddling for nothing. Forget about it until the weekend comes.
Things finally start looking up on Saturday the 19th. The swell arrives from the southeast with a long 16-second period and a solid 5ft building through the day. The energy is strong, hitting 2013 (moderate energy) in the morning and settling at 1023 (moderate energy) by the afternoon. That’s a proper groundswell. With a moderate NNE offshore breeze, Saturday afternoon is where it's at for experienced surfers. It's still a bit raw in the morning, but the afternoon cleans right up.
Sunday the 20th keeps the energy going with 5ft SSE swell at 12 seconds. The morning is clean with a light NNE offshore breeze, energy at 608 (moderate energy). Very good conditions. The afternoon gets a bit tricky with a cross-onshore breeze, so get your session in early.
Monday the 21st is a real standout. We’ve got 4ft of S swell at 12 seconds, but the real beauty is the wind – glassy, absolutely dead calm in the morning and afternoon. That's as clean as it gets. Energy is solid at 701 (moderate energy) in the morning and 477 (moderate energy) in the afternoon. This is the best of the run for sheer perfection.
Tuesday the 22nd offers more, with 5ft to 5ft SSW swell at 13 seconds. Morning has a clean cross-off breeze and good energy at 664 (moderate energy). Afternoon gets onshore and messy, so again, go early.
Water temp is sitting at 82°F, which feels a touch warmer than normal for this time of year. Not crazy unusual, but a nice bonus.
Don't even look at the 23rd – a serious storm system swings in with a near gale, 8ft swell, and it's completely blown out. That's a kiter's day, not a surfer's. The swell drops away fast after that, and we're back to tiny dribble for the rest of the outlook.
So, top picks for this period: Sunday the 20th morning and Monday the 21st morning. Monday gets the nod for the glassy, perfect conditions. The swell is solid but not too heavy, and the wind is a dream. It's a reef break, so it’ll handle that long-period SE swell well.
Rusty
Short Range ForecastLight rain (total 6mm), mostly falling on Sat morning. Warm (max 27°C on Mon morning, min 20°C on Sat morning). Winds increasing (calm on Sun morning, fresh winds from the S by Mon afternoon). | Days 4-6 Weather SummaryLight rain (total 2mm), mostly falling on Wed afternoon. Warm (max 26°C on Tue afternoon, min 21°C on Thu night). Winds increasing (light winds from the SSW on Tue afternoon, fresh winds from the NNE by Thu night). | ||||||||||||||||||||
Saturday 12 | Sunday 13 | Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | |||||||||||||||
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) | SSW 7 | SSW 7 | SSW 7 | SSW 7 | SSW 7 | SE 8 | SE 7 | S 4 | SE 9 | SSE 8 | SE 8 | SSE 7 | SE 8 | SE 8 | SE 8 | SSE 8 | SSE 9 | SE 8 | SE 9 | SE 16 | SE 18 |
Wave Graph  | |||||||||||||||||||||
 kJ | 18 | 18 | 9 | 5 | 15 | 15 | 11 | 28 | 29 | 27 | 16 | 19 | 16 | 18 | 17 | 6 | 8 | 9 | 3 | 10 | 150 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | off | off | off | on | on | on | on | cross-on | on | on | off | off | off | off | off | off | off | off | off | off |
High Tide | 5:41PM1.48m | 5:41AM1.58m | 6:03PM1.50m | 6:24AM1.58m | 6:25PM1.51m | 7:08AM1.53m | 6:48PM1.52m | 7:55AM1.46m | 7:12PM1.51m | 8:47AM1.38m | 7:38PM1.50m | 9:52AM1.29m | 8:06PM1.47m | ||||||||
Low Tide | 11:24AM0.37m | 11:34PM0.56m | 11:58AM0.45m | 00:08AM0.45m | 12:29PM0.55m | 00:43AM0.37m | 12:59PM0.67m | 1:21AM0.32m | 1:28PM0.80m | 2:02AM0.31m | 1:57PM0.92m | 2:48AM0.33m | 2:28PM1.03m | ||||||||
 |  |  |  |  |  | | |  | | | | | | | | |  | | | | |
 | 5:20 | — | — | 5:22 | — | — | 5:22 | — | — | 5:22 | — | — | 5:24 | — | — | 5:24 | — | — | 5:24 | — | — |
 | — | 5:53 | — | — | 5:52 | — | — | 5:51 | — | — | 5:50 | — | — | 5:47 | — | — | 5:46 | — | — | 5:45 | — |
mm | 4 | — | — | — | — | — | — | — | 2 | — | — | — | — | 2 | — | — | — | — | 1 | 1 | — |
Temp °C | 20 | 22 | 22 | 23 | 25 | 25 | 27 | 27 | 26 | 25 | 26 | 26 | 23 | 23 | 22 | 22 | 24 | 22 | 21 | 21 | 21 |
Feels °C | 20 | 23 | 23 | 26 | 26 | 27 | 26 | 26 | 27 | 25 | 27 | 28 | 25 | 25 | 22 | 20 | 23 | 19 | 16 | 17 | 18 |
Swell 1 Height (m) Direction Period (s) | SSW 7 | SSW 7 | SSW 7 | SSW 7 | SE 9 | SE 8 | SE 7 | SE 10 | SE 9 | SSE 8 | SE 8 | SSE 7 | SE 8 | SE 8 | SE 8 | SSE 8 | SSE 9 | SSE 8 | SE 8 | SE 8 | SE 18 |
| kJ | 18 | 18 | 9 | 5 | 12 | 15 | 11 | 15 | 29 | 27 | 16 | 19 | 16 | 18 | 17 | 6 | 8 | 7 | 3 | 3 | 150 |
Swell 2 Height (m) Direction Period (s) | SE 10 | SE 10 | SE 9 | SE 7 | E 13 | SW 7 | SE 9 | E 12 | S 7 | S 7 | E 14 | E 13 | SE 9 | E 13 | E 12 | ESE 8 | SE 8 | SE 8 | SE 9 | SE 8 | SE 8 |
| kJ | 4 | 4 | 3 | 2 | 3 | 2 | 3 | 11 | 1 | 1 | 4 | 13 | 3 | 13 | 3 | 6 | 2 | 9 | 3 | 2 | 11 |
Swell 3 Height (m) Direction Period (s) | S 8 | E 14 | E 13 | SE 9 | SSW 7 | E 12 | E 12 | E 15 | S 7 | S 7 | E 14 | S 7 | S 6 | S 8 | S 7 | SE 10 | E 11 | SSE 9 | — | SE 16 | S 11 |
| kJ | 1 | 4 | 4 | 3 | 5 | 3 | 3 | 4 | 1 | 1 | 16 | 1 | 1 | 1 | 1 | 4 | 2 | 7 | — | 10 | 2 |
Wind waves Height (m) Direction Period (s) | NE 3 | NNE 2 | NNE 2 | — | SSW 7 | SSW 3 | SSW 2 | S 4 | SSW 4 | — | S 3 | — | — | — | NE 3 | NE 3 | NNE 3 | NNE 3 | N 4 | N 4 | N 4 |
| kJ | 1 | 1 | 1 | — | 15 | 2 | 1 | 28 | 9 | — | 3 | — | — | — | 3 | 5 | 6 | 9 | 17 | 18 | 14 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 54 | 51 | 38 | 16 | 18 | 38 | 90 | 77 | 38 | 18 | 76 | 16 | 51 | 51 | 51 | 145 | 145 | 470 | 228 | 491 | 552 |
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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