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Surf Forecasts:
Rock Island surfForecast / Kanagawa / Japan
48hr Weather and Surf, issued 2 pm Wednesday 20 May 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
20.3° C
(Which is slightly cooler than normal)How big are the waves at Rock Island today?
The current surf forecast for Rock Island at 6PM is: 0.8m 4s primary swell from a South direction and 0.3m 10s secondary swell from a Southeast direction (forecast issued at 02:00pm May 20). The wind direction is predicted to be onshore.
| Time (JST) & Date | Wave Height | Wave Period |
|---|---|---|
| Morning (20 May) | - | - |
| Afternoon (20 May) | 2.5ft (0.8m) | 4s |
| Evening (20 May) | 1ft (0.3m) | 10s |
Table - waves today at Rock Island. (Swell directed towards the surf break)
Updates in hr min s Forecast update imminent
Short Range ForecastModerate rain (total 19mm), heaviest on Thu afternoon. Warm (max 23°C on Wed afternoon, min 14°C on Fri morning). Winds increasing (light winds from the NNW on Thu afternoon, strong winds from the N by Fri morning). | ||||||||||||||||||||||||
Wed 20 | Thursday 21 | Friday 22 | Sat 23 | |||||||||||||||||||||
12 PM | 3 PM | 6 PM | 9 PM | 12 AM | 3 AM | 6 AM | 9 AM | 12 PM | 3 PM | 6 PM | 9 PM | 12 AM | 3 AM | 6 AM | 9 AM | 12 PM | 3 PM | 6 PM | 9 PM | 12 AM | 3 AM | 6 AM | 9 AM | |
Swell Height Map |    |    |    |    | ||||||||||||||||||||
SE 10 | S 4 | S 4 | SE 10 | SE 10 | SE 9 | S 6 | ESE 9 | S 7 | SSW 7 | SSW 7 | SSW 8 | S 8 | SSW 8 | S 8 | S 8 | S 8 | S 8 | S 7 | SSW 7 | S 7 | S 7 | S 7 | S 7 | |
27 | 22 | 24 | 15 | 14 | 14 | 25 | 58 | 152 | 338 | 417 | 196 | 138 | 94 | 72 | 57 | 57 | 41 | 28 | 18 | 9 | 9 | 8 | 9 | |
Wind (km/h) | ||||||||||||||||||||||||
on | on | on | on | on | on | on | on | on | cross-off | off | off | cross-off | off | off | off | off | off | off | off | off | off | off | off | |
High Tide | 8:34PM1.32m | 6:22AM1.38m | 9:23PM1.28m | 7:05AM1.31m | 10:14PM1.25m | 7:58AM1.23m | ||||||||||||||||||
Low Tide | 1:09PM-0.06m | 1:18AM0.98m | 1:53PM0.01m | 2:07AM0.99m | 2:39PM0.11m | 3:10AM0.97m | ||||||||||||||||||
 |  |  |  |  |  |  | | |  |  | | | | | | | | | | | | | | |
 | — | — | — | — | — | 4:33 | — | — | — | — | — | — | — | 4:33 | — | — | — | — | — | — | — | 4:31 | — | — |
 | — | — | 6:42 | — | — | — | — | — | — | — | 6:43 | — | — | — | — | — | — | — | 6:43 | — | — | — | — | 6:44 |
— | — | — | — | 1 | 2 | 1 | 1 | — | 6 | 1 | 1 | 2 | 1 | 1 | 1 | — | 1 | — | — | — | — | — | — | |
Temp °C | 23 | 23 | 23 | 22 | 21 | 21 | 21 | 21 | 22 | 19 | 18 | 17 | 16 | 15 | 15 | 14 | 14 | 15 | 14 | 14 | 14 | 14 | 14 | 14 |
21 | 21 | 21 | 20 | 20 | 20 | 21 | 21 | 21 | 19 | 16 | 13 | 12 | 10 | 9 | 7 | 6 | 7 | 7 | 7 | 8 | 8 | 8 | 8 | |
Swell 1 Height (m) Direction Period (s) | SE 10 | SE 10 | SE 10 | SE 10 | SE 10 | SE 9 | SE 9 | ESE 9 | ESE 10 | S 7 | S 7 | SSW 8 | S 8 | SSW 8 | S 8 | S 8 | S 8 | S 8 | S 7 | SSW 7 | S 7 | S 7 | S 7 | S 7 |
 kJ | 27 | 16 | 15 | 15 | 14 | 14 | 14 | 58 | 38 | 181 | 209 | 196 | 138 | 94 | 72 | 57 | 57 | 41 | 28 | 18 | 9 | 9 | 8 | 9 |
Swell 2 Height (m) Direction Period (s) | — | — | — | SSE 5 | S 6 | — | — | — | — | — | — | SE 10 | SE 9 | SE 9 | SE 11 | SE 11 | SE 11 | SE 11 | SE 11 | E 11 | SSW 8 | SW 8 | SW 8 | E 11 |
| kJ | — | — | — | 7 | 1 | — | — | — | — | — | — | 4 | 3 | 3 | 4 | 4 | 4 | 4 | 4 | 2 | 6 | 2 | 2 | 2 |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | E 11 | SE 11 | — | — | — | — | ESE 10 | E 9 | SE 11 | E 11 | E 11 | E 6 |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | 2 | 5 | — | — | — | — | 18 | 6 | 5 | 2 | 2 | 1 |
Wind waves Height (m) Direction Period (s) | S 4 | S 4 | S 4 | S 4 | S 4 | SSW 3 | S 6 | S 6 | S 7 | SSW 7 | SSW 7 | — | NE 3 | NNE 3 | NNE 3 | NNE 3 | NNE 4 | N 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 |
| kJ | 13 | 22 | 24 | 13 | 8 | 4 | 25 | 52 | 152 | 338 | 417 | — | 4 | 7 | 4 | 9 | 17 | 18 | 19 | 21 | 16 | 13 | 12 | 8 |
Nearest Offshore or Glassy | ||||||||||||||||||||||||
Distance (km) | 491 | 491 | 38 | 38 | 38 | 38 | 38 | 14 | 14 | 2 | 0 | 38 | 38 | 136 | 228 | 145 | 145 | 145 | 145 | 145 | 145 | 572 | 798 | 798 |
Best forecast wave conditions in Kanagawa | ||||||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||||||
Header Global | ||||||||||||||||||||||||
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