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Surf Forecasts:
Rock Island surfForecast / Kanagawa / Japan
48hr Weather and Surf, issued 8 am 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
20.3° C
(Which is slightly cooler than normal)How big are the waves at Rock Island today?
The current surf forecast for Rock Island at 5PM is: 2.0m 7s primary swell from a South-southwest direction and 1.4m 7s secondary swell from a South direction, 0.4m 10s secondary swell from a East-southeast direction (forecast issued at 08:00am May 21). The wind direction is predicted to be offshore.
| Time (JST) & Date | Wave Height | Wave Period |
|---|---|---|
| Morning (21 May) | 3ft (0.9m) | 6s |
| Afternoon (21 May) | 6.5ft (2.0m) | 7s |
| Evening (21 May) | 4ft (1.2m) | 8s |
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 16mm), heaviest on Thu afternoon. Warm (max 22°C on Thu morning, min 13°C on Fri afternoon). Winds decreasing (strong winds from the NNE on Fri morning, light winds from the NNE by Sat night). | ||||||||||||||||||||||||
Thursday 21 | Friday 22 | Saturday 23 | Sun 24 | |||||||||||||||||||||
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 | 6 PM | 9 PM | 12 AM | 3 AM | |
Swell Height Map |    |    |    |    | ||||||||||||||||||||
S 6 | S 6 | S 7 | SSW 7 | S 7 | S 8 | SSW 8 | S 8 | S 8 | S 8 | S 7 | S 7 | SSW 7 | SSW 7 | S 7 | S 7 | SE 11 | S 7 | SE 11 | SE 11 | S 7 | SE 6 | SE 6 | SE 6 | |
21 | 57 | 145 | 404 | 215 | 177 | 104 | 76 | 57 | 55 | 40 | 28 | 18 | 18 | 10 | 4 | 5 | 5 | 5 | 5 | 5 | 10 | 23 | 18 | |
Wind (km/h) | ||||||||||||||||||||||||
on | on | on | cross-off | off | cross-off | off | off | off | off | off | off | off | off | off | off | off | off | off | off | cross-off | cross-off | cross-off | off | |
High Tide | 6:22AM1.38m | 9:23PM1.28m | 7:05AM1.31m | 10:14PM1.25m | 7:58AM1.23m | 11:05PM1.24m | ||||||||||||||||||
Low Tide | 1:53PM0.01m | 2:07AM0.99m | 2:39PM0.11m | 3:10AM0.97m | 3:31PM0.23m | |||||||||||||||||||
 |  |  |  | |  | |  | | | | | | | | | | | | | | | | | |
 | 4:33 | — | — | — | — | — | — | 4:33 | — | — | — | — | — | — | — | 4:31 | — | — | — | — | — | — | — | 4:31 |
 | — | — | — | — | 6:43 | — | — | — | — | — | — | — | 6:43 | — | — | — | — | — | — | — | 6:44 | — | — | 6:45 |
1 | 1 | — | 6 | 1 | 1 | 1 | — | — | 1 | 1 | 1 | 1 | — | — | — | — | — | — | — | — | — | — | — | |
Temp °C | 21 | 21 | 22 | 19 | 17 | 17 | 16 | 16 | 16 | 15 | 14 | 14 | 13 | 13 | 13 | 13 | 13 | 14 | 16 | 19 | 19 | 19 | 18 | 18 |
21 | 20 | 21 | 17 | 13 | 13 | 12 | 12 | 11 | 8 | 6 | 6 | 5 | 6 | 7 | 6 | 7 | 8 | 11 | 16 | 17 | 17 | 17 | 17 | |
Swell 1 Height (m) Direction Period (s) | SE 9 | ESE 9 | ESE 10 | S 7 | S 7 | S 8 | SSW 8 | S 8 | S 8 | S 8 | S 7 | S 7 | SSW 7 | SSW 7 | S 7 | S 7 | SE 11 | S 7 | SE 7 | N 3 | ESE 6 | SE 6 | E 12 | SE 6 |
 kJ | 14 | 56 | 63 | 220 | 215 | 177 | 104 | 76 | 57 | 55 | 40 | 28 | 18 | 18 | 10 | 4 | 5 | 4 | 2 | 1 | 4 | 10 | 3 | 18 |
Swell 2 Height (m) Direction Period (s) | — | — | — | — | ESE 10 | SE 10 | SE 10 | SE 10 | SE 11 | SE 9 | SE 10 | SE 11 | SE 11 | E 9 | E 11 | SW 8 | SE 8 | SE 7 | S 7 | SE 6 | S 7 | SE 11 | S 8 | SE 12 |
| kJ | — | — | — | — | 37 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 5 | 2 | 2 | 2 | 2 | 2 | 1 | 1 | 4 | 5 | 1 | 5 |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | SE 11 | — | E 11 | — | SSE 7 | — | E 11 | E 9 | E 11 | S 6 | SE 11 | SE 11 | SE 11 | SE 11 | — | SE 12 | — |
| kJ | — | — | — | — | — | — | — | 5 | — | 2 | — | 9 | — | 2 | 2 | 2 | 1 | 5 | 5 | 5 | 5 | — | 6 | — |
Wind waves Height (m) Direction Period (s) | S 6 | S 6 | S 7 | SSW 7 | — | NE 3 | NE 3 | NE 3 | NNE 3 | NNE 3 | NNE 4 | NNE 4 | NNE 4 | NE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NNE 4 | NE 3 | — | — | SE 6 | — |
| kJ | 21 | 57 | 145 | 404 | — | 2 | 4 | 5 | 4 | 7 | 17 | 26 | 29 | 24 | 20 | 13 | 12 | 10 | 10 | 2 | — | — | 23 | — |
Nearest Offshore or Glassy | ||||||||||||||||||||||||
Distance (km) | 92 | 491 | 86 | 2 | 38 | 38 | 38 | 8 | 145 | 145 | 145 | 509 | 470 | 552 | 755 | 801 | 798 | 798 | 885 | 885 | 64 | 755 | 38 | 38 |
Best forecast wave conditions in Kanagawa | ||||||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||||||
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