Surf Forecasts:
Rock Island surf forecast from 14 Sep 2026:
- Best quality surf: Sunday 20 Sep, 9AM (local time) - 5.5ft (1.7m), 13s period, SSE swell with offshore winds.
- Most powerful swell: Monday 21 Sep, 12PM (local time) - 6ft (1.9m), 14s period, S swell with 1,431 kJ wave energy.
- Next surfable swell (1★+): Tuesday 15 Sep, 9PM (local time) - 2ft (0.6m), 6s period with SSW 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 Tuesday (Sep 15) at 9PM. The primary swell is predicted to be 0.5m and 7s period with a secondary swell of 0.5m and 5s. Another secondary swell of 0.6m and 6s 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 1.9m 14s and forecast to arrive on Monday (Sep 21) at 12PM. 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 Thursday (Sep 17) at 9PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Tue 15th Sep) | 2ft (0.6m) 6s |
| Best Surf | 9AM (Sun 20th Sep) | 5.5ft (1.7m) 13s |
| Most Powerful | 12PM (Mon 21st Sep) | 6ft (1.9m) 14s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
Alright, Rusty here, lookin’ at the charts for our stretch of coast. Let’s cut through the noise.
Right now, it’s a tough watch. We’ve got a long stretch of flatness and blown-out junk to get through first. From today through to the 18th of September, it’s basically a write-off. Tiny little knee-high slop at best, mostly onshore and messy. The water’s sitting at 81°, which is a touch warmer than normal for this time of year – nothing wild, just a little extra warmth in the water.
The first real glimmer of hope doesn’t show up until the morning of Saturday the 19th. The wind finally swings offshore from the north, cleaning things right up. We see chest to head high swell starting to build, 6ft from the southeast with a solid 15-second period. That’s proper groundswell energy starting to pulse (combined energy of 1359). It’s clean, but the tide and other factors keep it from being epic just yet. It keeps building through Sunday the 20th, pushing 7ft from the SSE, same long period, and the energy jumps up (2012). The wind stays offshore. It’s good, but it's still a bit raw.
Now, the standout. The real highlight is Monday the 21st of September. That’s the day. We get a solid 8ft to 10ft swell from the south, with that lovely 14-second period, and the energy is pumping – we’re talking over 3000 (combined energy of 3022 and 3747). This is serious, powerful groundswell. The wind stays clean offshore, light to moderate from the north-northeast. This is for experienced surfers only, though; at over 8ft, it’s no place for beginners. With that long period and south swell direction lining up, Rock Island (a reef) should be handling this beautifully. Expect some proper stand-up sets and long walls. The offshore breeze will make it glassy and perfect. Just know that crowds are possible here on a day like this.
After that Monday peak, it drops away fast. Tuesday the 22nd is a shadow of what came before, with the swell dropping to less than 3ft. Then it’s back to small, weak, and mostly poor surf all the way through the end of the run. A few clean mornings here and there, but nothing worth paddling out for. It’s a classic case of a short, powerful spike and then a long, slow fade.
Rusty.
Short Range ForecastHeavy rain (total 64mm), heaviest during Wed night. Warm (max 27°C on Mon afternoon, min 19°C on Wed night). Winds decreasing (strong winds from the SSW on Mon afternoon, light winds from the SSW by Tue afternoon). | Days 5-7 Weather SummaryHeavy rain (total 51mm), heaviest during Sat afternoon. Warm (max 23°C on Sun morning, min 18°C on Thu night). Mainly fresh winds. | |||||||||||||||||||
Mon 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | ||||||||||||||
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 4 | E 14 | SE 8 | SE 7 | SE 7 | SSE 7 | SE 8 | SE 8 | SSE 8 | SSE 8 | SE 8 | SE 16 | SE 16 | SE 14 | SE 14 | SE 13 | SSE 12 | SSE 13 | SSE 13 | S 13 |
Wave Graph  | ||||||||||||||||||||
 kJ | 28 | 34 | 24 | 16 | 23 | 9 | 17 | 17 | 7 | 7 | 9 | 10 | 306 | 676 | 722 | 535 | 680 | 1042 | 745 | 865 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | cross-on | on | off | off | off | off | off | off | off | off | off | off | off | cross-off | cross-off | off | off | off |
High Tide | 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 | 11:24AM1.23m | 8:42PM1.41m | 1:35PM1.24m | 9:38PM1.34m | |||||||
Low Tide | 00:43AM0.37m | 12:59PM0.67m | 1:21AM0.32m | 1:28PM0.80m | 2:02AM0.31m | 1:57PM0.92m | 2:48AM0.33m | 2:28PM1.03m | 3:44AM0.37m | 3:06PM1.13m | 4:55AM0.41m | 4:31PM1.21m | ||||||||
 |  |  |  |  | |  |  |  | |  | | |  | |  | | | | | |
 | — | — | 5:22 | — | — | 5:24 | — | — | 5:24 | — | — | 5:24 | — | — | 5:26 | — | — | 5:26 | — | — |
 | 5:51 | — | — | 5:50 | — | — | 5:47 | — | — | 5:46 | — | — | 5:45 | — | — | 5:44 | — | — | 5:43 | — |
mm | — | 4 | 3 | 3 | 8 | 3 | 10 | 33 | — | — | — | — | — | — | 9 | 25 | 17 | — | — | — |
Temp °C | 27 | 26 | 24 | 24 | 24 | 21 | 21 | 20 | 19 | 20 | 19 | 21 | 22 | 21 | 21 | 20 | 21 | 23 | 23 | 22 |
Feels °C | 25 | 26 | 25 | 26 | 27 | 20 | 20 | 17 | 15 | 15 | 14 | 15 | 17 | 17 | 16 | 16 | 19 | 23 | 23 | 22 |
Swell 1 Height (m) Direction Period (s) | SE 10 | SE 9 | SE 8 | SE 7 | SE 7 | SSW 6 | SE 8 | SE 8 | SSE 8 | SSE 8 | SE 9 | SE 8 | SE 16 | SE 14 | SE 14 | SE 13 | SSE 12 | SSE 13 | SSE 13 | S 13 |
| kJ | 15 | 22 | 24 | 14 | 23 | 7 | 17 | 17 | 7 | 7 | 3 | 3 | 306 | 676 | 722 | 535 | 680 | 1042 | 745 | 865 |
Swell 2 Height (m) Direction Period (s) | E 12 | E 14 | S 7 | E 14 | SSW 6 | SSE 7 | SSW 6 | S 5 | SE 7 | — | SE 8 | SE 16 | ESE 9 | E 8 | — | SSE 15 | S 9 | — | S 15 | SE 10 |
| kJ | 11 | 33 | 1 | 4 | 11 | 9 | 3 | 2 | 2 | — | 9 | 10 | 15 | 12 | — | 266 | 2 | — | 275 | 207 |
Swell 3 Height (m) Direction Period (s) | E 15 | E 14 | S 7 | E 14 | E 13 | SE 7 | SSW 6 | E 12 | S 5 | E 7 | SE 9 | S 13 | — | — | — | — | — | — | — | — |
| kJ | 4 | 34 | 1 | 16 | 13 | 9 | 6 | 3 | 1 | 1 | 3 | 3 | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | S 4 | SSW 4 | SSW 4 | S 4 | — | NE 3 | NE 3 | NNE 3 | NNE 3 | NE 3 | NE 4 | NNE 4 | NNE 4 | N 4 | NNE 4 | N 3 | NNE 3 | — | NNE 3 | NNE 3 |
| kJ | 28 | 27 | 5 | 15 | — | 2 | 1 | 8 | 6 | 7 | 14 | 16 | 16 | 13 | 11 | 6 | 3 | — | 8 | 3 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 142 | 76 | 38 | 76 | 38 | 38 | 51 | 228 | 145 | 552 | 470 | 228 | 145 | 228 | 145 | 72 | 10 | 0 | 0 | 0 |
Best forecast wave conditions in Kanagawa | ||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||
Header Global | ||||||||||||||||||||
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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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