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Surf Forecasts:
Rock Island surfForecast / Kanagawa / Japan
48hr Weather and Surf, issued 8 am Monday 18 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
19.7° C
(Which is slightly cooler than normal)How big are the waves at Rock Island today?
The current surf forecast for Rock Island at 1PM is: 0.3m 10s primary swell from a Southeast direction and 0.3m 8s secondary swell from a Southeast direction, 0.1m 10s secondary swell from a Southeast direction, 0.3m 2s secondary swell from a South direction (forecast issued at 08:00am May 18). The wind direction is predicted to be onshore.
| Time (JST) & Date | Wave Height | Wave Period |
|---|---|---|
| Morning (18 May) | 0.5ft (0.2m) | 8s |
| Afternoon (18 May) | 1ft (0.3m) | 10s |
| Evening (18 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 ForecastMostly dry. Warm (max 23°C on Wed afternoon, min 19°C on Mon night). Winds decreasing (fresh winds from the S on Tue afternoon, calm by Wed night). | ||||||||||||||||||||||||
Monday 18 | Tuesday 19 | Wednesday 20 | Thu 21 | |||||||||||||||||||||
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 |    |    |    |    | ||||||||||||||||||||
ESE 8 | SSE 8 | SE 10 | SE 10 | SE 10 | SE 10 | SSE 7 | ESE 10 | SE 10 | SE 10 | SE 11 | S 4 | SSW 4 | SE 11 | SE 11 | SE 11 | SE 11 | SE 10 | SE 10 | SE 10 | SE 10 | SE 10 | SE 10 | SE 9 | |
7 | 6 | 17 | 16 | 16 | 16 | 10 | 10 | 16 | 29 | 18 | 35 | 43 | 29 | 29 | 29 | 40 | 38 | 37 | 26 | 25 | 24 | 23 | 14 | |
Wind (km/h) | ||||||||||||||||||||||||
glassy | cross-on | on | on | on | on | on | on | on | on | on | on | on | on | on | on | cross-on | on | on | on | on | glassy | glassy | cross-off | |
High Tide | 4:38AM1.42m | 7:00PM1.37m | 5:10AM1.43m | 7:46PM1.35m | 5:44AM1.42m | 8:34PM1.32m | ||||||||||||||||||
Low Tide | 11:49AM-0.09m | 11:59PM0.91m | 12:29PM-0.09m | 00:37AM0.95m | 1:09PM-0.06m | 1:18AM0.98m | ||||||||||||||||||
 | | | | |  | | | | | | | | |  | | |  | |  | |  | | | |
 | 4:35 | — | — | — | — | — | — | 4:35 | — | — | — | — | — | — | — | 4:33 | — | — | — | — | — | — | — | 4:33 |
 | — | — | — | — | 6:39 | — | — | — | — | — | — | — | 6:40 | — | — | — | — | — | — | — | 6:42 | — | — | 6:43 |
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | |
Temp °C | 19 | 20 | 21 | 21 | 21 | 21 | 20 | 19 | 19 | 20 | 21 | 22 | 22 | 21 | 20 | 20 | 20 | 21 | 22 | 22 | 23 | 23 | 21 | 21 |
19 | 19 | 17 | 17 | 17 | 17 | 17 | 17 | 18 | 17 | 16 | 17 | 18 | 18 | 18 | 19 | 20 | 21 | 22 | 21 | 24 | 25 | 23 | 22 | |
Swell 1 Height (m) Direction Period (s) | ESE 8 | SSE 8 | SE 8 | SE 8 | SSE 7 | SE 7 | SSE 7 | ESE 10 | SE 10 | SE 10 | SE 11 | SE 11 | SE 11 | SE 11 | SE 11 | SE 11 | SE 11 | SE 10 | SE 10 | SE 10 | SE 10 | SE 10 | SE 10 | SE 9 |
 kJ | 7 | 6 | 9 | 9 | 5 | 8 | 5 | 10 | 16 | 28 | 18 | 18 | 18 | 29 | 29 | 29 | 40 | 38 | 37 | 26 | 25 | 24 | 23 | 14 |
Swell 2 Height (m) Direction Period (s) | SSE 7 | ESE 8 | SE 10 | SE 10 | ESE 10 | SE 10 | ESE 10 | SSE 7 | SSE 7 | ESE 9 | ESE 9 | E 10 | — | — | — | — | — | — | — | S 8 | S 8 | S 4 | SSW 3 | S 3 |
| kJ | 5 | 6 | 4 | 4 | 10 | 4 | 10 | 5 | 4 | 29 | 16 | 8 | — | — | — | — | — | — | — | 1 | 1 | 1 | 1 | 1 |
Swell 3 Height (m) Direction Period (s) | SE 10 | SE 10 | SE 10 | SE 10 | SE 10 | SE 10 | SSE 7 | E 9 | — | — | — | — | — | — | — | — | — | — | — | — | — | S 8 | S 4 | S 6 |
| kJ | 4 | 4 | 17 | 16 | 16 | 16 | 9 | 6 | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 | 1 | 1 |
Wind waves Height (m) Direction Period (s) | — | — | — | S 3 | S 3 | S 3 | SSW 3 | SSW 3 | SW 3 | SSW 3 | S 4 | S 4 | SSW 4 | SSW 4 | SSW 4 | SSW 4 | SSW 4 | SSW 4 | SSW 3 | SSW 4 | SSW 4 | SSW 4 | — | — |
| kJ | — | — | — | 4 | 8 | 6 | 4 | 4 | 2 | 4 | 13 | 35 | 43 | 26 | 16 | 11 | 6 | 2 | 3 | 4 | 3 | 2 | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||||||
Distance (km) | 16 | 16 | 76 | 77 | 77 | 90 | 90 | 38 | 38 | 90 | 518 | 518 | 38 | 38 | 38 | 38 | 38 | 18 | 77 | 77 | 38 | 38 | 16 | 38 |
Best forecast wave conditions in Kanagawa | ||||||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||||||
Header Global | ||||||||||||||||||||||||
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