Nazare Big Wave Challenge Gets Yellow Alert, Could Run Saturday in Giant Waves
70-foot plus waves predicted for Portuguese big wave tow surfing competition.
Surf Forecasts:
Rock Island surfForecast / Kanagawa / Japan
48hr Weather and Surf, issued 8 pm Saturday 13 Dec 2025 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
18.1° C
(Which is 1.3°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 12AM is: 0.1m 6s primary swell from a Southeast direction and 0.1m 5s secondary swell from a Southeast direction (forecast issued at 08:00pm December 13). An open ocean swell of 0.3m 2s is not directed at the surf break. The wind direction is predicted to be offshore.
| Time (JST) & Date | Wave Height | Wave Period |
|---|---|---|
| Morning (14 Dec) | 2ft (0.6m) | 7s |
| Afternoon (14 Dec) | 4.5ft (1.4m) | 10s |
| Evening (14 Dec) | 7ft (2.1m) | 8s |
Table - waves today at Rock Island. (Swell directed towards the surf break)
Updates in hr min s Forecast update imminent
Sat 13 | Sunday 14 | Monday 15 | Tuesday 16 | |||||||||||||||||||||
| 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 | 6 AM | 9 AM | 12 PM | 3 PM | |
Rating (10 max) | ||||||||||||||||||||||||
Swell Height Map |   |    |    |    | ||||||||||||||||||||
| Wave Height (m) & direction (?) | ||||||||||||||||||||||||
| Period(s) (?) | 11 | 11 | 11 | 6 | 6 | 7 | 7 | 10 | 10 | 8 | 10 | 9 | 9 | 10 | 10 | 9 | 9 | 9 | 9 | 8 | 8 | 8 | 8 | 8 |
Wave (?)Graph  | ||||||||||||||||||||||||
 kJ (?) | 2 | 2 | 2 | 10 | 19 | 30 | 43 | 349 | 1144 | 545 | 274 | 550 | 110 | 98 | 36 | 22 | 21 | 20 | 12 | 11 | 7 | 7 | 7 | 7 |
Wind (km/h) | ||||||||||||||||||||||||
| Wind State (?) onshore cross-onshore cross-shore cross-offshore offshore glassy | cross- off | off | off | off | off | off | cross- off | glass | cross | cross- on | cross- off | cross | cross- off | cross- off | cross- off | cross- off | off | off | off | cross- off | off | off | glass | cross- on |
High Tide / height (m) | 11:07PM 1.11 | 12:01PM 1.31 | 12:49AM 1.10 | 12:41PM 1.32 | 2:21AM 1.15 | 1:19PM 1.35 | ||||||||||||||||||
Low Tide / height (m) | 5:39PM 0.76 | 5:16AM 0.61 | 6:45PM 0.62 | 6:20AM 0.74 | 7:42PM 0.47 | 7:25AM 0.84 | ||||||||||||||||||
Sat 13 | Sunday 14 | Monday 15 | Tuesday 16 | |||||||||||||||||||||
| Sunrise | - | - | - | - | - | 6:41 | - | - | - | - | - | - | - | 6:41 | - | - | - | - | - | - | - | 6:43 | - | - |
| Sunset | - | - | - | - | - | - | - | 4:30 | - | - | - | - | - | - | - | 4:30 | - | - | - | - | - | - | - | 4:30 |
 | |  | | |  |  |  |  | | | | |  | |  |  | | | | | | | | |
Rain (mm) | - | - | 1 | - | 3 | 8 | 4 | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
| Temp. °C | 7 | 7 | 6 | 6 | 6 | 6 | 8 | 10 | 13 | 12 | 12 | 11 | 10 | 10 | 12 | 12 | 11 | 10 | 9 | 9 | 7 | 7 | 9 | 10 |
| Feels °C (?) | 2 | 1 | -1 | -1 | 0 | -1 | 3 | 8 | 9 | 9 | 8 | 6 | 5 | 5 | 9 | 8 | 4 | 4 | 4 | 4 | 1 | 2 | 6 | 7 |
- Map Icons:
Break
Live Wave Height (m)
Live Wind Speed (km/h)
Surf Rating (10 Max)
Ocean Swells (m)- Wind Speed (km/h)
Latest Updates
Buy Less, Surf More This Black Friday
Surf-forecast is providing a free, all-access pass to our premium features and 12-day forecasts all weekend.
Quiksilver Teams Up With PrimaLoft® For World’s First Thermal Layering System for a Wetsuit.
Previously used in our snow jackets for mountain conditions, PrimaLoft® technology is making its debut in the surf industry. The aim is to bring mountain-grade warmth to the waves.
Vancouver Island’s Day Of Days With Reed Platenius
Surf-Forecast recently helped the 21-year-old Canadian pro surfer and adventurer score some cold water perfection at home.
Read more
Discover more articles and updates in the Greenroom.
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.
Nearest