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Surf Forecasts:
Rock Island surfForecast / Kanagawa / Japan
12 Day Weather and Surf, issued 8 am Tuesday 16 Dec 2025 JSTForecast update in hr min s Forecast update imminent
Rock Island surf forecast is for near shore open water. Breaking waves will often be smaller at less exposed spots.
Today's Rock Island sea temperature is
17.8° C
(Which is 1.5°C colder than average for this time of year)Best Forecast Surf Conditions for Rock Island this week:
The surf forecast for Rock Island over the next 12 days: The first swell (rated 1 star or higher) is forecast to arrive on Wednesday (Dec 17) at 3PM. The primary swell is predicted to be 1.1m and 6s period with a secondary swell of 0.3m and 4s. Another secondary swell of 0.1m and 7s 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 12 days are 1.7m 7s and forecast to arrive on Sunday (Dec 21) 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 0.9m 4s period and expected on Monday (Dec 22) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Wed 17th Dec) | 3.5ft (1.1m) 6s |
| Best Surf | 3PM (Wed 17th Dec) | 3.5ft (1.1m) 6s |
| Most Powerful | 6PM (Sun 21st Dec) | 5.5ft (1.7m) 7s |
Table - best surf conditions forecast for Rock Island over the next 12 days.
Updates in hr min s Forecast update imminent
Short Range Forecast Mostly dry. Very mild (max 13°C on Wed night, min 7°C on Tue morning). Wind will be generally light. | Days 3-6 Weather Summary Moderate rain (total 10mm), heaviest on Sun night. Very mild (max 18°C on Sat afternoon, min 8°C on Fri morning). Winds increasing (calm on Fri night, fresh winds from the SSW by Sun night). | ||||||||||||||||||||
Tuesday 16 | Wednesday 17 | Thursday 18 | Friday 19 | Saturday 20 | Sunday 21 | Monday 22 | |||||||||||||||
| AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | |
Rating (10 max) | |||||||||||||||||||||
Swell Height Map |  |  |  |  |  |  |  | ||||||||||||||
| Wave Height (m) & direction (?) | |||||||||||||||||||||
| Period(s) (?) | 8 | 8 | 7 | 4 | 6 | 5 | 6 | 6 | 10 | 11 | 11 | 5 | 5 | 5 | 6 | 6 | 7 | 7 | 9 | 9 | 8 |
Wave (?)Graph  | |||||||||||||||||||||
 kJ (?) | 7 | 6 | 5 | 2 | 69 | 54 | 3 | 3 | 2 | 5 | 2 | 28 | 22 | 20 | 60 | 136 | 219 | 176 | 154 | 106 | 35 |
Wind (km/h) | |||||||||||||||||||||
| Wind State (?) onshore cross-onshore cross-shore cross-offshore offshore glassy | off | off | on | cross- off | off | cross- off | off | off | cross- off | off | off | glass | cross- on | on | on | on | on | on | off | off | off |
High Tide / height (m) | 1:19PM 1.35 | 3:35AM 1.23 | 1:59PM 1.38 | 4:35AM 1.30 | 2:38PM 1.41 | 5:25AM 1.36 | 3:18PM 1.45 | 6:10AM 1.40 | 3:58PM 1.47 | 6:51AM 1.42 | 4:39PM 1.48 | 7:30AM 1.41 | 5:22PM 1.47 | ||||||||
Low Tide / height (m) | 8:34PM 0.32 | 8:26AM 0.92 | 9:20PM 0.18 | 9:21AM 0.98 | 10:04PM 0.06 | 10:10AM 1.02 | 10:46PM -0.02 | 10:55AM 1.04 | 11:26PM -0.07 | 11:37AM 1.04 | 12:07AM -0.07 | 12:19PM 1.02 | 12:47AM -0.04 | ||||||||
Tuesday 16 | Wednesday 17 | Thursday 18 | Friday 19 | Saturday 20 | Sunday 21 | Monday 22 | |||||||||||||||
| Sunrise | 6:43 | - | - | 6:43 | - | - | 6:43 | - | - | 6:43 | - | - | 6:45 | - | - | 6:46 | - | - | 6:46 | - | - |
| Sunset | - | 4:30 | - | - | 4:30 | - | - | 4:30 | - | - | 4:30 | - | - | 4:31 | - | - | 4:31 | - | - | 4:32 | - |
 |  |  | | |  | | | | | | |  | |  |  | |  |  | | | |
Rain (mm) | - | - | - | - | - | - | - | - | - | - | - | - | - | - | 1 | 2 | 1 | 6 | 31 | 2 | - |
| Temp. °C | 8 | 9 | 12 | 10 | 11 | 13 | 9 | 10 | 11 | 9 | 10 | 13 | 15 | 18 | 18 | 18 | 18 | 16 | 13 | 10 | 8 |
| Feels °C (?) | 2 | 5 | 8 | 7 | 9 | 10 | 2 | 4 | 6 | 4 | 7 | 12 | 12 | 13 | 13 | 15 | 15 | 11 | 9 | 0 | -3 |
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The surf report / weather widget below is available to embed on third party websites free of charge and provides a summary of our Rock Island surf forecast. Simply grab the html code snippet that we provide and paste it into your own site. You can choose your preferred language and metric/imperial units for the surf forecast feed to suit users of your site. Click here to get the code.
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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 12 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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