Surf Forecasts:
Rock Island surf forecast from 21 Jul 2026:
- Best quality surf: Thursday 23 Jul, 3AM (local time) - 3ft (0.9m), 6s period, SW swell with offshore winds.
- Most powerful swell: Thursday 23 Jul, 3AM (local time) - 3ft (0.9m), 6s period, SW swell with 46 kJ wave energy.
- Next surfable swell (1★+): Thursday 23 Jul, 3AM (local time) - 3ft (0.9m), 6s period with SW 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 (Jul 23) at 3AM. The primary swell is predicted to be 0.9m and 6s period with a secondary swell of 0.6m and 5s. Another secondary swell of 0.1m and 11s is also forecast. 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 0.9m 6s and forecast to arrive on Thursday (Jul 23) at 3AM. Winds are predicted to be offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.1m 5s period and expected on Tuesday (Jul 28) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Thu 23rd Jul) | 3ft (0.9m) 6s |
| Best Surf | 3AM (Thu 23rd Jul) | 3ft (0.9m) 6s |
| Most Powerful | 3AM (Thu 23rd Jul) | 3ft (0.9m) 6s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright folks, Rusty here. It’s looking like a quiet stretch ahead for us, so let’s get into it.
First up, we’ve got Rock Island. The water temp is sitting at about 80.2°, a touch warmer than normal for this time of year, so the tropical feel is a bonus. The whole 16-day window starts off with a long flat spell. From now until the end of July, there’s just nothing doing. Tiny waves, no energy, and a lot of onshore slop. It’s a real bummer. You’ll see a few days with glassy mornings, like Saturday the 25th morning with a light offshore from the NE, but the swell is only 0.3m (1ft). It’s clean but not worth paddling out for.
That gap stretches all the way until the first of August, and even then it’s marginal. The first little pulse of life shows up on Saturday morning, August 1st, with a 0.9m (3ft) SSE swell, period ticking up to 13 seconds, and combined energy of 326 (moderate). The wind is light cross-onshore, so it’s not perfect, but it’s at least a sign of something. Rock Island starts to get a bit more interesting by Sunday, August 2nd morning. Swell pushes to 1.2m (4ft) from the S, period 13 seconds, and energy jumps to 517 (strong). Wind is still light cross-onshore though, so it’s a bit lumpy.
The real standout, the one you circle on the calendar, is Tuesday morning, August 4th. That’s the best we’ve got. Rock Island will see a 1.6m (5.2ft) SSW swell, period 14 seconds, and combined energy of 988 (strong). The wind is a light cross-offshore from the ENE, which should keep things clean. That’s your window. It’s a reef break, so that long period groundswell will wrap in nicely, and for a spot that’s fairly consistent, it’s worth the wait. The 1.6m (5.2ft) swell is a bit much for beginners, but for the crew who know what they’re doing, it’s prime.
After that, it backs off again. Wednesday morning, August 5th, drops to 0.9m (3ft) from the SSW, energy down to 216 (moderate), and wind is light cross-onshore. Not a write-off, but not the highlight.
Bottom line: the first week is a dead zone. Get your gear ready for the 4th of August. That’s the one.
Short Range ForecastLight rain (total 4mm), mostly falling on Thu night. Warm (max 32°C on Thu morning, min 26°C on Thu night). Wind will be generally light. | Days 5-7 Weather SummaryModerate rain (total 17mm), heaviest on Fri night. Warm (max 28°C on Fri afternoon, min 23°C on Sat night). Wind will be generally light. | |||||||||||||||||||
Tue 21 | Wednesday 22 | Thursday 23 | Friday 24 | Saturday 25 | Sunday 26 | Monday 27 | ||||||||||||||
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 4 | SSW 4 | SSW 4 | S 4 | SSW 5 | SSW 6 | SSW 6 | SSE 10 | SSE 9 | SSE 9 | SE 11 | SE 10 | SE 10 | SSE 15 | SE 15 | SE 11 | SE 11 | SE 10 | SE 10 | SE 10 |
Wave Graph  | ||||||||||||||||||||
 kJ | 12 | 11 | 12 | 6 | 19 | 15 | 8 | 12 | 12 | 11 | 18 | 15 | 15 | 22 | 8 | 18 | 20 | 16 | 16 | 16 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | on | on | on | cross-off | cross-on | cross-off | cross | on | cross-off | cross-off | off | cross-off | glassy | on | on | on | on | on |
High Tide | 9:33PM1.40m | 10:14AM1.18m | 10:05PM1.39m | 11:48AM1.12m | 10:43PM1.38m | 1:49PM1.13m | 11:30PM1.38m | 3:34PM1.21m | 00:29AM1.39m | 4:34PM1.30m | 1:35AM1.40m | 5:13PM1.37m | 2:38AM1.44m | |||||||
Low Tide | 3:07PM0.59m | 4:07AM0.58m | 3:45PM0.75m | 5:11AM0.52m | 4:29PM0.91m | 6:22AM0.44m | 5:30PM1.04m | 7:33AM0.35m | 7:05PM1.13m | 8:36AM0.25m | 8:38PM1.16m | 9:30AM0.16m | 9:45PM1.13m | |||||||
 |  |  | | | | |  | | | |  |  |  | |  | |  | |  | |
 | — | — | 4:41 | — | — | 4:43 | — | — | 4:43 | — | — | 4:43 | — | — | 4:45 | — | — | 4:46 | — | — |
 | 6:53 | — | — | 6:52 | — | — | 6:52 | — | — | 6:52 | — | — | 6:51 | — | — | 6:50 | — | — | 6:50 | — |
mm | — | — | — | — | — | — | — | 4 | — | — | 6 | — | 1 | 1 | — | 2 | 4 | 3 | — | 1 |
Temp °C | 29 | 29 | 29 | 29 | 29 | 32 | 31 | 28 | 28 | 28 | 27 | 25 | 25 | 24 | 25 | 26 | 24 | 26 | 26 | 26 |
Feels °C | 31 | 32 | 34 | 32 | 32 | 35 | 34 | 33 | 31 | 30 | 31 | 26 | 25 | 25 | 27 | 28 | 26 | 28 | 27 | 29 |
Swell 1 Height (m) Direction Period (s) | SE 8 | SE 8 | SSW 4 | SE 8 | SE 11 | SSW 6 | SSW 6 | S 5 | SSE 9 | SSE 9 | SE 11 | SE 10 | SE 10 | SE 10 | SE 15 | SE 11 | S 9 | SSE 4 | SSW 8 | SSW 8 |
| kJ | 3 | 2 | 6 | 2 | 5 | 13 | 8 | 2 | 8 | 8 | 18 | 15 | 15 | 15 | 8 | 18 | 13 | 3 | 14 | 14 |
Swell 2 Height (m) Direction Period (s) | E 11 | SE 11 | SE 8 | SE 11 | S 7 | SSE 10 | SE 10 | SSE 10 | S 8 | SSW 7 | SE 16 | SE 16 | SE 16 | SSE 4 | SE 11 | SE 15 | SE 11 | SSW 9 | SE 10 | SE 10 |
| kJ | 2 | 4 | 2 | 5 | 1 | 10 | 4 | 9 | 4 | 5 | 10 | 10 | 10 | 1 | 5 | 8 | 18 | 15 | 16 | 16 |
Swell 3 Height (m) Direction Period (s) | ESE 11 | — | SE 11 | SE 11 | SE 7 | SE 19 | S 8 | SE 18 | SE 18 | SE 17 | SW 7 | — | S 7 | SSE 15 | SE 9 | S 9 | SSE 14 | SE 10 | SSE 4 | SE 13 |
| kJ | 12 | — | 4 | 4 | 2 | 15 | 1 | 12 | 12 | 11 | 2 | — | 1 | 22 | 3 | 6 | 20 | 16 | 1 | 7 |
Wind waves Height (m) Direction Period (s) | SSW 4 | SSW 4 | SSW 4 | S 4 | SSW 5 | — | — | — | — | — | SSE 3 | — | SSE 2 | — | SSE 4 | S 3 | S 3 | — | — | — |
| kJ | 10 | 11 | 12 | 6 | 19 | — | — | — | — | — | 1 | — | 1 | — | 2 | 8 | 4 | — | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 1425 | 76 | 76 | 1438 | 76 | 51 | 51 | 51 | 51 | 77 | 51 | 51 | 470 | 51 | 16 | 18 | 38 | 18 | 77 | 18 |
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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