Surf Forecasts:
Rock Island surf forecast from 5 Sep 2026:
- Best quality surf: Tuesday 8 Sep, 9AM (local time) - 4.5ft (1.3m), 9s period, S swell with glassy winds.
- Most powerful swell: Monday 7 Sep, 6PM (local time) - 8ft (2.5m), 9s period, S swell with 1,016 kJ wave energy.
- Next surfable swell (1★+): Monday 7 Sep, 6AM (local time) - 3.5ft (1.1m), 10s 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 6AM. The primary swell is predicted to be 1.1m and 10s period with a secondary swell of 0.9m and 8s. 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 Monday (Sep 07) at 6PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.8m 4s period and expected on Sunday (Sep 06) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Mon 7th Sep) | 3.5ft (1.1m) 10s |
| Best Surf | 9AM (Tue 8th Sep) | 4.5ft (1.3m) 9s |
| Most Powerful | 6PM (Mon 7th Sep) | 8ft (2.5m) 9s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright, Rusty here. Let's talk about Rock Island. This is a reef break that's exposed to southerly swells, and it's best when the wind is coming out of the north-northeast. It's a fairly consistent spot, but right now it's a bit of a waiting game.
First up, the water is running at 83°, which is a touch warmer than normal for this time of year.
The next few days are pretty much a write-off. Sunday the 6th has a tiny, weak swell from the SSE with an energy reading of 19, and it's getting battered by a stiff offshore breeze that's making it near impossible to paddle into. The wave comment is "poor surf conditions." Monday the 7th gets worse with a big, messy 8ft to 8ft SSE swell under strong cross-onshore and onshore winds—that is a kiter's setup, not a paddle surfer's, with energy jumping up to 1015.
Now, here's the one true standout: Tuesday, September 8th. The morning is the absolute pick of the entire forecast. The wind goes completely glassy out of the northwest at only 3 mph, and we get a clean 4ft swell from the south with a 9-second period and moderate energy of 555. The wave comment says "expect very good surf conditions." The afternoon holds onto the glassy conditions with a 4ft south swell and energy of 287, so you could get a solid session in. This is the day to go.
After that, Wednesday the 9th turns ugly again with a 6ft south-southwest swell and onshore wind (energy at 867). The conditions get pretty average for a while after. Thursday the 10th morning has a small clean 4ft south swell with light offshore wind, but the wave comment is only "surfable waves but very ordinary conditions." From Friday the 11th all the way through to about Sunday the 20th, we’re in a long dry spell. The swell drops to a pathetic 0.7ft to 2ft with low energy readings (8 to 97) and while the wind is occasionally offshore, the surf is just too small and weak to get excited about. It's a real gap of over a week where there's nothing worth paddling out for.
Looking further out, Monday the 21st shows a slight uptick, with a 3ft south-southwest swell and clean cross-offshore wind, but with an energy of 160 it's still "surfable waves but very ordinary conditions." Not a standout, more of a last resort. So, the bottom line: your only real window is Tuesday the 8th—everything else is a bust for Rock Island.
Rusty.
Short Range ForecastHeavy rain (total 236mm), heaviest during Sun night. Warm (max 27°C on Mon morning, min 21°C on Sun afternoon). Winds decreasing (near gales from the SSW on Mon afternoon, calm by Tue morning). | Days 4-6 Weather SummaryLight rain (total 8mm), mostly falling on Wed night. Warm (max 27°C on Wed morning, min 20°C on Fri morning). Winds decreasing (fresh winds from the N on Wed afternoon, light winds from the SSW by Thu morning). | ||||||||||||||||||||
Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | Friday 11 | Saturday 12 | |||||||||||||||
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) | SSE 8 | SE 8 | SE 8 | SSE 8 | S 9 | S 9 | S 9 | S 9 | SSW 10 | SSW 9 | SSW 9 | S 9 | S 9 | S 8 | S 8 | S 8 | S 7 | S 7 | S 8 | S 8 | SSW 10 |
Wave Graph  | |||||||||||||||||||||
 kJ | 7 | 16 | 98 | 737 | 994 | 526 | 276 | 181 | 135 | 543 | 344 | 270 | 185 | 136 | 80 | 40 | 27 | 17 | 20 | 18 | 20 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | off | off | cross-on | on | on | glassy | glassy | cross-on | on | cross-on | off | off | on | off | off | off | off | off | cross-off | off |
High Tide | 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 | 4:08AM1.50m | 5:19PM1.47m | 4:56AM1.56m | 5:41PM1.48m | ||||||||
Low Tide | 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 | 10:49AM0.32m | 11:01PM0.69m | 11:24AM0.37m | 11:34PM0.56m | ||||||||
 |  |  |  | |  | | |  | | |  |  | |  |  | | | | |  | |
 | 5:16 | — | — | 5:16 | — | — | 5:18 | — | — | 5:18 | — | — | 5:20 | — | — | 5:20 | — | — | 5:20 | — | — |
 | — | 6:02 | — | — | 6:00 | — | — | 6:00 | — | — | 5:58 | — | — | 5:57 | — | — | 5:55 | — | — | 5:53 | — |
mm | 2 | 46 | 110 | 50 | 16 | 5 | 3 | 1 | 3 | 1 | 3 | 4 | — | — | — | — | — | — | — | — | — |
Temp °C | 23 | 22 | 22 | 27 | 27 | 26 | 26 | 25 | 26 | 27 | 27 | 22 | 22 | 24 | 21 | 21 | 23 | 23 | 24 | 26 | 24 |
Feels °C | 19 | 18 | 22 | 25 | 24 | 28 | 31 | 30 | 29 | 30 | 30 | 20 | 24 | 27 | 19 | 20 | 24 | 24 | 25 | 28 | 25 |
Swell 1 Height (m) Direction Period (s) | SSE 8 | SE 8 | SE 8 | — | E 8 | S 9 | S 9 | S 9 | SSE 8 | SSW 10 | SSE 8 | S 9 | S 9 | S 8 | S 8 | S 8 | S 7 | S 7 | S 8 | S 8 | SSW 10 |
| kJ | 7 | 16 | 98 | — | 21 | 526 | 276 | 181 | 99 | 205 | 76 | 270 | 185 | 136 | 80 | 40 | 27 | 17 | 20 | 18 | 20 |
Swell 2 Height (m) Direction Period (s) | ESE 7 | SSE 8 | S 9 | — | — | E 8 | SSE 9 | SSW 9 | SSW 10 | SSE 8 | SE 10 | ESE 9 | — | ESE 10 | SE 9 | E 10 | SE 10 | S 9 | SE 10 | SE 10 | SSW 13 |
| kJ | 5 | 12 | 83 | — | — | 10 | 252 | 66 | 135 | 116 | 24 | 8 | — | 10 | 3 | 2 | 4 | 6 | 4 | 4 | 16 |
Swell 3 Height (m) Direction Period (s) | SSW 8 | S 8 | S 11 | — | — | SE 10 | SE 10 | SW 11 | ESE 10 | E 12 | E 16 | SE 11 | E 15 | E 15 | E 16 | S 9 | S 8 | E 10 | E 14 | S 11 | S 7 |
| kJ | 7 | 1 | 41 | — | — | 25 | 27 | 40 | 10 | 3 | 5 | 5 | 4 | 17 | 5 | 1 | 1 | 2 | 4 | 3 | 4 |
Wind waves Height (m) Direction Period (s) | NE 4 | NE 4 | NNE 4 | SSE 8 | S 9 | — | — | — | — | SSW 9 | SSW 9 | NNE 3 | NNE 3 | NNE 3 | NNE 3 | — | — | — | — | — | — |
| kJ | 14 | 16 | 11 | 737 | 994 | — | — | — | — | 543 | 344 | 5 | 3 | 3 | 1 | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 488 | 470 | 552 | 488 | 136 | 14 | 0 | 0 | 7 | 14 | 12 | 29 | 0 | 14 | 0 | 51 | 51 | 51 | 16 | 16 | 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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