Surf Forecasts:
Rock Island surf forecast from 16 Aug 2026:
- Best quality surf: Sunday 16 Aug, 3PM (local time) - 1.5ft (0.5m), 9s period, S swell with cross-offshore winds.
- Most powerful swell: Saturday 22 Aug, 12PM (local time) - 3.5ft (1.1m), 10s period, S swell with 245 kJ wave energy.
- Next surfable swell (1★+): Sunday 16 Aug, 3PM (local time) - 1.5ft (0.5m), 9s period with S swell.
Best Forecast Surf Conditions for Rock Island this week:
The surf forecast for Rock Island over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Sunday (Aug 16) at 3PM. The primary swell is predicted to be 0.5m and 9s period with a secondary swell of 0.2m and 11s. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Rock Island in the next 16 days are 1.1m 10s and forecast to arrive on Saturday (Aug 22) at 12PM. Winds are predicted to be onshore at the time the swell arrives.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Sun 16th Aug) | 1.5ft (0.5m) 9s |
| Best Surf | 3PM (Sun 16th Aug) | 1.5ft (0.5m) 9s |
| Most Powerful | 12PM (Sat 22nd Aug) | 3.5ft (1.1m) 10s |
Table - best surf conditions forecast for Rock Island over the next 16 days.
The Lowdown
G’day, Rusty here.
Well, I’ll be honest with ya – this outlook for Rock Island is a tough one. The first week and a half is pretty much a write-off for any kind of decent paddle surfing. We’ve got some tiny, weak swell and mostly onshore or cross-onshore winds spoiling what little there is. There’s a real dry spell from Sunday the 16th of August right through to late on Tuesday the 25th of August, with barely a wave worth paddling for. If you’re into kites, maybe the breezy afternoons with a bit of chop could be your thing, but for a surfboard, it’s a no-go.
The water temp is sitting at 81°F – that’s pretty normal for this time of year, so no surprises there.
Now, the one bright spot in the whole 16-day run is Wednesday the 26th of August. Mark it in the calendar. Early morning, Rock Island cleans right up – glassy conditions, light offshore wind out of the ENE, and a solid 6 ft groundswell rolling in from the SSE with a very long period of 15 seconds. The combined energy of all swells directed here is strong at 1284. That’s proper, powerful, clean surf, but at that size and with this break being a reef setup, it’s really only for experienced surfers. The long period means the waves will have heaps of energy and shape, and with glassy surface, it’s the standout session of the whole window. Crowds are possible here, so get in early.
The days surrounding that window are hit-and-miss. By the 27th and 28th of August, the swell jumps up over 7 ft, but the wind shifts cross-onshore and the conditions turn lumpy and choppy – not worth it unless you’re a masochist. The energy numbers climb into the thousands, but poor wind spoils the party.
After that, the swell fades quickly into the end of the month, with a quick glimpse on the 31st of August of a clean but tiny 1 ft swell and offshore wind – a small window for the longboard if you’re desperate.
So bottom line: hang tight, wait for Wednesday morning the 26th of August, and if you’re experienced, that’s your day. Otherwise, it’s a long flat spell.
Stay salty,
Rusty
Short Range ForecastLight rain (total 5mm), mostly falling on Sun afternoon. Warm (max 28°C on Tue afternoon, min 24°C on Sun night). Wind will be generally light. | Days 4-6 Weather SummaryMostly dry. Warm (max 28°C on Wed afternoon, min 25°C on Wed night). Winds increasing (calm on Wed night, fresh winds from the S by Fri afternoon). | ||||||||||||||||||||
Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | |||||||||||||||
AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | |
Swell Height Map |  |  |  |  |  |  |  | ||||||||||||||
Wave Height (m) Direction Period (s) | SSW 9 | S 9 | S 9 | S 9 | ESE 8 | SSW 8 | ESE 10 | SE 7 | SE 7 | SE 7 | SSE 6 | SSE 6 | SE 10 | SE 11 | SSW 9 | SSW 10 | S 9 | SSW 11 | SSW 10 | SSW 5 | SSW 5 |
Wave Graph  | |||||||||||||||||||||
 kJ | 28 | 39 | 37 | 23 | 48 | 13 | 10 | 8 | 7 | 7 | 4 | 4 | 4 | 29 | 27 | 54 | 83 | 103 | 80 | 66 | 59 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | cross-off | cross-off | cross-off | on | cross-off | cross-off | on | cross | cross-off | cross-on | cross-on | glassy | on | on | on | on | on | on | on | on |
High Tide | 7:18PM1.48m | 7:12AM1.50m | 7:41PM1.48m | 8:00AM1.43m | 8:06PM1.47m | 8:53AM1.34m | 8:32PM1.46m | 9:59AM1.24m | 9:00PM1.45m | 11:32AM1.17m | 9:36PM1.42m | 1:55PM1.18m | 10:25PM1.38m | ||||||||
Low Tide | 12:57PM0.34m | 1:12AM0.59m | 1:28PM0.46m | 1:51AM0.52m | 1:59PM0.61m | 2:34AM0.48m | 2:29PM0.75m | 3:23AM0.45m | 3:00PM0.90m | 4:23AM0.44m | 3:34PM1.04m | 5:36AM0.43m | 4:30PM1.15m | ||||||||
 |  |  | | |  | | |  |  | | | | | | | | | | | | |
 | 5:01 | — | — | 5:01 | — | — | 5:01 | — | — | 5:03 | — | — | 5:03 | — | — | 5:05 | — | — | 5:05 | — | — |
 | — | 6:30 | — | — | 6:29 | — | — | 6:28 | — | — | 6:27 | — | — | 6:24 | — | — | 6:23 | — | — | 6:22 | — |
mm | — | 2 | 1 | 2 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 26 | 27 | 25 | 27 | 27 | 26 | 27 | 28 | 26 | 27 | 28 | 26 | 27 | 27 | 26 | 27 | 27 | 27 | 28 | 28 | 27 |
Feels °C | 27 | 28 | 27 | 30 | 29 | 28 | 30 | 30 | 29 | 30 | 29 | 28 | 29 | 28 | 28 | 28 | 27 | 27 | 27 | 27 | 26 |
Swell 1 Height (m) Direction Period (s) | SSW 9 | S 9 | S 9 | S 9 | S 8 | SSW 8 | SSE 6 | SE 7 | SE 7 | SE 7 | SE 10 | SE 10 | SE 10 | SSW 10 | SSW 9 | SSW 10 | SSW 12 | SSW 11 | SSW 10 | SE 10 | SE 10 |
| kJ | 28 | 39 | 37 | 23 | 22 | 13 | 4 | 8 | 7 | 7 | 4 | 4 | 4 | 20 | 27 | 54 | 55 | 103 | 80 | 4 | 4 |
Swell 2 Height (m) Direction Period (s) | SE 7 | SSE 11 | SSE 11 | SE 11 | SE 11 | SSE 6 | SSW 8 | SSW 8 | SSW 8 | SE 10 | SE 7 | SSE 6 | SE 6 | ESE 10 | ESE 10 | ESE 10 | ESE 10 | ESE 10 | SE 10 | SE 10 | SE 11 |
| kJ | 14 | 12 | 12 | 5 | 4 | 3 | 6 | 6 | 6 | 4 | 2 | 3 | 1 | 11 | 10 | 10 | 10 | 10 | 4 | 4 | 5 |
Swell 3 Height (m) Direction Period (s) | SSE 12 | E 10 | E 8 | E 9 | E 8 | SE 10 | ESE 10 | SE 10 | SE 10 | SSW 8 | SW 8 | SE 6 | SW 8 | SE 11 | — | SE 10 | SE 7 | S 9 | SE 11 | SSE 10 | — |
| kJ | 14 | 2 | 1 | 1 | 1 | 4 | 10 | 4 | 4 | 6 | 3 | 2 | 2 | 29 | — | 28 | 13 | 2 | 5 | 10 | — |
Wind waves Height (m) Direction Period (s) | NNE 2 | — | — | — | ESE 8 | — | — | — | — | — | SSE 6 | — | — | SSE 2 | SSE 3 | SSE 4 | S 9 | S 4 | S 4 | SSW 5 | SSW 5 |
| kJ | 1 | — | — | — | 48 | — | — | — | — | — | 4 | — | — | 1 | 1 | 2 | 83 | 6 | 9 | 66 | 59 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 0 | 0 | 0 | 64 | 16 | 51 | 51 | 18 | 51 | 51 | 18 | 51 | 51 | 18 | 18 | 76 | 77 | 14 | 142 | 518 | 491 |
Best forecast wave conditions in Kanagawa | |||||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||||
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Information about the Rock Island Surf forecast
The above surf forecast table for Rock Island provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Rock Island can be found by selecting the local surf guide option on the grey menu. Our Rock Island surf forecast is unique since it includes wave energy (power) that defines the real feel of the surf rather than just the height or the period. If you surf the same spot (Rock Island) regularly then make a mental note of the wave energy from the surf forecast table each time you go. Very soon you may start to choose your surf days based on the wave energy alone combined with our forecast of favourable offshore wind conditions. Our star ratings will help here and of course you will also find the usual wave height and period predictions on our surf forecasts as well as a full break down of the swell components under our advanced users option (to reveal that, click the little Einstein character under the tide times).
Further information to help with frequently asked questions about our surf forecast for Rock Island may be found under the help tab on the top menu and also by moving your mouse over the question marks on the surf forecast table itself. Please always bear in mind that the forecast is for near-shore open water and local factors at each surf break influence the actual breaking wave height, such as the beach / reef profile, water depths offshore and shelter.
Rock Island is 3 km (2 miles) from the city of Kamakura. If you plan a holiday in Kanagawa, look for hotels and other accommodation in Kamakura. Kamakura has rooms for a wide range of budgets as well as car hire and transport links.
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