
Surf Forecasts:
Rock Island surf forecast from 6 Aug 2026:
- Best quality surf: Sunday 9 Aug, 6AM (local time) - 2.5ft (0.7m), 10s period, S swell with glassy winds.
- Most powerful swell: Friday 7 Aug, 9AM (local time) - 5ft (1.6m), 13s period, S swell with 810 kJ wave energy.
- Next surfable swell (1★+): Sunday 9 Aug, 6AM (local time) - 2.5ft (0.7m), 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 Sunday (Aug 09) at 6AM. The primary swell is predicted to be 0.7m and 10s period with a secondary swell of 0.3m and 13s. 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 1.6m 13s and forecast to arrive on Friday (Aug 07) at 9AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.5m 3s period and expected on Thursday (Aug 13) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Sun 9th Aug) | 2.5ft (0.7m) 10s |
| Best Surf | 6AM (Sun 9th Aug) | 2.5ft (0.7m) 10s |
| Most Powerful | 9AM (Fri 7th Aug) | 5ft (1.6m) 13s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s chew the fat on Rock Island. It’s a reef break that needs a south swell to light up, and it’s exposed to it. The water is sitting at 80°, which is dead average for this time of year, so nothing to write home about.
We kick off with the first surfable window on Friday the 7th of August. The morning has a 5ft southerly swell with a 13-second period, which is a nice groundswell. The energy is moderate at 962. The wind is a light cross-on from the SSE at 6 mph, so it’s a little bumpy. It’s rideable, but it’s not blowing the doors off.
Saturday the 8th is a step down. The morning shows a 4ft southerly swell, but the wind is onshore at 12 mph, so it’s choppy. The energy drops to 324. The afternoon is worse with the same onshore wind and 3ft surf. Not worth suiting up.
Sunday the 9th is a tease. The morning has a 2ft SSW swell, but the wind is glassy from the east at 3 mph. It’s as clean as a whistle, but the waves are tiny. The energy is only 151. The afternoon goes onshore again.
From Monday the 10th right through to Friday the 21st of August, it’s a long, flat stretch. The swell drops from 2ft down to a pathetic 0.7ft. The wind is often offshore and clean, but with waves that small, you’re just floating around. The energy drops into the double digits, which is weak as dishwater. There’s a tiny blip on the morning of the 16th with a 2ft SSW swell and 126 energy, but it’s still just knee-high.
The one and only standout in this whole 16-day run is the very end. On Saturday the 22nd of August, we finally get a pulse. The morning has a 2ft southerly swell with an 11-second period, and the energy climbs to 153. The wind is a clean cross-off from the NE at 9 mph. The afternoon is even better: the swell holds at 2ft, but the wind goes directly offshore from the NE. That’s clean, glassy faces. For a reef break, an offshore wind and a bit of south swell is the best you’ll get. Crowds are just a possibility, so you might snag a few waves alone.
So, the bottom line: there’s a massive gap of almost two weeks of poor to flat surf. The only real window to get excited about is that Saturday the 22nd. It’s not a bomb, but it’s the cleanest and most fun stretch on offer. Keep your board handy.
Rusty.
Short Range ForecastMostly dry. Warm (max 28°C on Fri morning, min 25°C on Sat night). Wind will be generally light. | Days 4-6 Weather SummaryModerate rain (total 10mm), heaviest on Wed night. Warm (max 29°C on Mon afternoon, min 24°C on Mon night). Mainly fresh winds. | ||||||||||||||||||||
Friday 7 | Saturday 8 | Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | Thursday 13 | |||||||||||||||
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 13 | S 12 | S 11 | S 11 | S 11 | SSW 11 | SSW 10 | S 10 | S 10 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 11 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 9 |
Wave Graph | |||||||||||||||||||||
810 | 625 | 418 | 307 | 242 | 194 | 112 | 75 | 77 | 93 | 91 | 83 | 63 | 66 | 95 | 68 | 35 | 33 | 41 | 39 | 17 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | cross-on | on | on | cross-on | glassy | on | cross-off | cross-off | glassy | cross-off | cross-on | on | on | cross-on | cross-on | cross-off | off | cross-off | off |
High Tide | 12:41PM1.13m | 10:30PM1.40m | 2:57PM1.19m | 11:28PM1.38m | 4:09PM1.28m | 00:45AM1.38m | 4:47PM1.36m | 2:03AM1.40m | 5:17PM1.41m | 3:09AM1.45m | 5:43PM1.45m | 4:05AM1.50m | 6:08PM1.47m | ||||||||
Low Tide | 4:23PM1.04m | 6:37AM0.41m | 5:47PM1.15m | 7:52AM0.33m | 7:53PM1.19m | 8:54AM0.25m | 9:16PM1.16m | 9:46AM0.18m | 10:08PM1.08m | 10:31AM0.14m | 10:48PM0.99m | 11:12AM0.14m | 11:25PM0.88m | ||||||||
4:54 | — | — | 4:54 | — | — | 4:54 | — | — | 4:56 | — | — | 4:56 | — | — | 4:58 | — | — | 4:58 | — | — | |
— | 6:39 | — | — | 6:38 | — | — | 6:37 | — | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — | — | 6:34 | — | |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 2 | 5 | — | — | 2 |
Temp °C | 28 | 28 | 27 | 28 | 28 | 26 | 28 | 28 | 27 | 27 | 29 | 26 | 25 | 26 | 26 | 28 | 27 | 26 | 28 | 29 | 27 |
Feels °C | 31 | 29 | 29 | 30 | 29 | 28 | 31 | 28 | 29 | 27 | 31 | 24 | 27 | 25 | 24 | 29 | 28 | 28 | 28 | 30 | 30 |
Swell 1 Height (m) Direction Period (s) | S 13 | S 12 | S 11 | S 11 | S 11 | SSW 11 | SSW 10 | S 10 | S 10 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 11 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 9 |
810 | 625 | 418 | 307 | 242 | 194 | 112 | 75 | 77 | 93 | 91 | 83 | 63 | 66 | 95 | 68 | 35 | 33 | 41 | 39 | 17 | |
Swell 2 Height (m) Direction Period (s) | ESE 9 | ESE 9 | SE 12 | ESE 11 | ESE 12 | ESE 12 | ESE 13 | ESE 13 | ESE 12 | ESE 12 | ESE 11 | ESE 11 | SW 12 | SW 12 | SE 10 | SSE 3 | SW 12 | SW 11 | SE 12 | E 12 | ESE 11 |
148 | 139 | 6 | 11 | 13 | 28 | 34 | 34 | 14 | 14 | 12 | 12 | 6 | 6 | 4 | 1 | 21 | 19 | 5 | 11 | 13 | |
Swell 3 Height (m) Direction Period (s) | E 15 | E 15 | E 15 | SE 12 | SE 12 | ESE 15 | SE 12 | SW 12 | SW 12 | SW 12 | SE 11 | SW 12 | SE 12 | SE 12 | SE 13 | SE 10 | — | SE 12 | E 10 | SE 12 | ESE 3 |
4 | 4 | 4 | 6 | 6 | 21 | 5 | 5 | 23 | 5 | 5 | 6 | 5 | 6 | 6 | 4 | — | 5 | 2 | 5 | 1 | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | S 3 | — | — | — | — | — | — | — | — | — | S 3 | SE 3 | — | NNE 3 | NNE 3 | NE 3 | — |
— | — | — | — | 2 | — | — | — | — | — | — | — | — | — | 1 | 1 | — | 3 | 5 | 2 | — | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 64 | 54 | 64 | 6 | 54 | 54 | 0 | 54 | 0 | 6 | 0 | 7 | 14 | 77 | 14 | 64 | 64 | 7 | 38 | 0 | 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.











