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Surf Forecasts:
Rock Island surfForecast / Kanagawa / Japan
48hr Weather and Surf, issued 8 am Saturday 18 Apr 2026 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
17.0° C
(Which is 1.2°C colder than average for this time of year)How big are the waves at Rock Island today?
The current surf forecast for Rock Island at 11AM is: 1.6m 16s primary swell from a South-southeast direction and 0.3m 11s secondary swell from a East direction (forecast issued at 08:00am April 18). The wind direction is predicted to be cross-onshore.
| Time (JST) & Date | Wave Height | Wave Period |
|---|---|---|
| Morning (18 Apr) | 5ft (1.6m) | 16s |
| Afternoon (18 Apr) | 5ft (1.5m) | 16s |
| Evening (18 Apr) | 4.5ft (1.4m) | 15s |
Table - waves today at Rock Island. (Swell directed towards the surf break)
Updates in hr min s Forecast update imminent
Saturday 18 | Sunday 19 | Monday 20 | Tue 21 | |||||||||||||||||||||
| 6 AM | 9 AM | 12 PM | 3 PM | 6 PM | 9 PM | 0 AM | 3 AM | 6 AM | 9 AM | 12 PM | 3 PM | 6 PM | 9 PM | 0 AM | 3 AM | 6 AM | 9 AM | 12 PM | 3 PM | 6 PM | 9 PM | 0 AM | 3 AM | |
Rating (10 max) | ||||||||||||||||||||||||
Swell Height Map |    |    |    |    | ||||||||||||||||||||
| Wave Height (m) & direction (?) | ||||||||||||||||||||||||
| Period(s) (?) | 16 | 16 | 16 | 16 | 15 | 15 | 15 | 15 | 14 | 14 | 15 | 15 | 14 | 14 | 14 | 14 | 14 | 14 | 13 | 13 | 13 | 12 | 12 | 12 |
Wave (?)Graph  | ||||||||||||||||||||||||
 kJ (?) | 1239 | 1224 | 1068 | 1041 | 845 | 869 | 869 | 857 | 845 | 899 | 911 | 911 | 961 | 961 | 947 | 822 | 701 | 595 | 451 | 380 | 277 | 221 | 146 | 141 |
Wind (km/h) | ||||||||||||||||||||||||
| Wind State (?) onshore cross-onshore cross-shore cross-offshore offshore glassy | glass | on | cross- on | on | on | cross- on | glass | glass | off | cross- off | cross- off | cross- on | on | cross | cross- off | cross- off | cross- off | cross- off | glass | cross- on | cross- on | cross- on | on | on |
High Tide / height (m) | 4:56AM 1.35 | 6:12PM 1.39 | 5:21AM 1.37 | 6:57PM 1.36 | 5:46AM 1.38 | 7:44PM 1.32 | ||||||||||||||||||
Low Tide / height (m) | 11:31AM 0.06 | 11:48PM 0.63 | 12:07PM -0.00 | 12:20AM 0.72 | 12:45PM -0.03 | 12:52AM 0.81 | ||||||||||||||||||
Saturday 18 | Sunday 19 | Monday 20 | Tue 21 | |||||||||||||||||||||
| Sunrise | 5:05 | - | - | - | - | - | - | - | 5:05 | - | - | - | - | - | - | - | 5:03 | - | - | - | - | - | - | - |
| Sunset | - | - | - | - | 6:15 | - | - | - | - | - | - | - | 6:16 | - | - | - | - | - | - | - | 6:16 | - | - | - |
 | | |  | |  |  |  |  | | | | | | | | | | | | | | | | |
Rain (mm) | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| Temp. °C | 14 | 15 | 16 | 17 | 17 | 17 | 16 | 16 | 16 | 17 | 20 | 20 | 19 | 17 | 17 | 16 | 16 | 16 | 18 | 18 | 17 | 17 | 17 | 16 |
| Feels °C (?) | 14 | 14 | 13 | 14 | 15 | 16 | 16 | 17 | 16 | 16 | 19 | 18 | 17 | 16 | 17 | 15 | 15 | 13 | 17 | 15 | 14 | 15 | 15 | 12 |
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Live Wave Height (m)
Live Wind Speed (km/h)
Surf Rating (10 Max)
Ocean Swells (m)- Wind Speed (km/h)
FREE! Surf-Forecast.com widget for your website
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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