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Surf Forecasts:
Rock Island surfForecast / Kanagawa / Japan
48hr Weather and Surf, issued 8 pm Thursday 21 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
20.8° C
(Which is normal for this time of year)How big are the waves at Rock Island today?
The current surf forecast for Rock Island at 1AM is: 0.9m 8s primary swell from a South direction and 0.1m 10s secondary swell from a Southeast direction (forecast issued at 08:00pm May 21). An open ocean swell of 0.4m 3s is not directed at the surf break. The wind direction is predicted to be offshore.
| Time (JST) & Date | Wave Height | Wave Period |
|---|---|---|
| Morning (22 May) | 2.5ft (0.7m) | 8s |
| Afternoon (22 May) | 1.5ft (0.5m) | 7s |
| Evening (22 May) | 1ft (0.3m) | 8s |
Table - waves today at Rock Island. (Swell directed towards the surf break)
Updates in hr min s Forecast update imminent
Short Range ForecastLight rain (total 9mm), mostly falling on Thu night. Warm (max 20°C on Sun morning, min 13°C on Fri afternoon). Winds decreasing (strong winds from the N on Fri afternoon, calm by Sat night). | ||||||||||||||||||||||||
Thu 21 | Friday 22 | Saturday 23 | Sunday 24 | |||||||||||||||||||||
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 | 12 PM | 3 PM | |
Swell Height Map |   |    |    |    | ||||||||||||||||||||
S 7 | S 8 | S 8 | S 8 | S 8 | S 8 | S 7 | S 7 | SSW 7 | S 8 | SSW 8 | SSE 6 | SSW 7 | SSE 7 | SSE 7 | SE 11 | ESE 6 | SE 7 | SE 6 | SE 6 | SE 6 | SSE 6 | SSE 6 | SSE 6 | |
183 | 142 | 95 | 76 | 57 | 55 | 40 | 28 | 18 | 10 | 6 | 4 | 5 | 5 | 5 | 5 | 5 | 7 | 56 | 62 | 18 | 26 | 26 | 26 | |
Wind (km/h) | ||||||||||||||||||||||||
cross-off | off | off | off | off | cross-off | off | off | off | off | off | off | off | off | off | off | cross | cross-off | cross-off | glassy | cross-off | cross-off | cross | cross-on | |
High Tide | 9:23PM1.28m | 7:05AM1.31m | 10:14PM1.25m | 7:58AM1.23m | 11:05PM1.24m | 9:12AM1.13m | ||||||||||||||||||
Low Tide | 2:07AM0.99m | 2:39PM0.11m | 3:10AM0.97m | 3:31PM0.23m | 4:29AM0.92m | |||||||||||||||||||
 |  | |  | | | | | | |  |  |  | |  | | | | | | | | | | |
 | — | — | — | 4:33 | — | — | — | — | — | — | — | 4:31 | — | — | — | — | — | — | — | 4:31 | — | — | — | — |
 | 6:43 | — | — | — | — | — | — | — | 6:43 | — | — | — | — | — | — | — | 6:44 | — | — | — | — | — | — | 6:45 |
1 | — | — | 3 | 1 | 1 | 1 | 2 | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | |
Temp °C | 17 | 16 | 16 | 16 | 16 | 15 | 15 | 14 | 13 | 13 | 13 | 13 | 13 | 14 | 16 | 19 | 19 | 18 | 18 | 18 | 18 | 19 | 20 | 20 |
13 | 12 | 12 | 12 | 11 | 8 | 7 | 5 | 5 | 5 | 6 | 6 | 7 | 8 | 11 | 16 | 16 | 15 | 17 | 18 | 18 | 19 | 20 | 19 | |
Swell 1 Height (m) Direction Period (s) | S 7 | S 8 | S 8 | S 8 | S 8 | S 8 | S 7 | S 7 | SSW 7 | S 8 | SSW 8 | SSE 6 | SSW 7 | SSE 7 | SSE 7 | SE 11 | ESE 6 | SE 7 | SE 6 | SE 6 | SE 6 | SSE 6 | SSE 6 | SSE 6 |
 kJ | 183 | 142 | 95 | 76 | 57 | 55 | 40 | 28 | 18 | 10 | 6 | 4 | 5 | 5 | 5 | 5 | 4 | 7 | 14 | 18 | 18 | 26 | 26 | 26 |
Swell 2 Height (m) Direction Period (s) | ESE 10 | ESE 10 | SE 11 | SE 9 | SE 10 | SE 10 | SE 10 | SE 11 | E 10 | E 9 | SE 6 | SE 11 | SSE 7 | SE 11 | SE 11 | S 6 | S 6 | SE 11 | E 12 | E 12 | E 12 | E 12 | E 12 | E 10 |
| kJ | 36 | 11 | 4 | 3 | 4 | 4 | 4 | 4 | 2 | 2 | 2 | 4 | 4 | 5 | 5 | 1 | 1 | 5 | 3 | 3 | 3 | 3 | 3 | 2 |
Swell 3 Height (m) Direction Period (s) | — | — | — | SE 11 | E 11 | — | E 6 | SSE 7 | E 11 | E 11 | SE 11 | S 8 | SE 11 | SE 8 | SE 7 | SE 6 | SE 11 | S 6 | SE 12 | SE 10 | SE 10 | ESE 10 | ESE 10 | E 12 |
| kJ | — | — | — | 5 | 3 | — | 1 | 9 | 2 | 2 | 4 | 1 | 5 | 2 | 2 | 1 | 5 | 1 | 6 | 4 | 4 | 10 | 10 | 3 |
Wind waves Height (m) Direction Period (s) | NE 2 | NE 3 | NE 3 | NE 3 | NNE 3 | NNE 3 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NE 3 | — | E 2 | SE 6 | SE 6 | — | — | — | — |
| kJ | 1 | 1 | 2 | 2 | 3 | 10 | 21 | 23 | 32 | 26 | 17 | 16 | 12 | 12 | 7 | 3 | — | 1 | 56 | 62 | — | — | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||||||
Distance (km) | 92 | 0 | 8 | 487 | 38 | 487 | 145 | 487 | 487 | 552 | 552 | 552 | 798 | 804 | 885 | 885 | 885 | 64 | 0 | 0 | 16 | 38 | 38 | 64 |
Best forecast wave conditions in Kanagawa | ||||||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||||||
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