Surf Forecasts:
Onjuku surf forecast from 11 Aug 2026:
- Best quality surf: Sunday 16 Aug, 9AM (local time) - 11ft (3.5m), 11s period, E swell with cross-offshore winds.
- Most powerful swell: Sunday 16 Aug, 12PM (local time) - 11ft (3.5m), 11s period, ENE swell with 2,767 kJ wave energy.
- Next surfable swell (1★+): Wednesday 12 Aug, 6PM (local time) - 4ft (1.2m), 9s period with E swell.
Best Forecast Surf Conditions for Onjuku this week:
The surf forecast for Onjuku over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Wednesday (Aug 12) at 6PM. The primary swell is predicted to be 1.2m and 9s period with a secondary swell of 0.6m and 6s. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 3.5m 11s and forecast to arrive on Sunday (Aug 16) at 12PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 2.5m 7s period and expected on Sunday (Aug 16) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6PM (Wed 12th Aug) | 4ft (1.2m) 9s |
| Best Surf | 9AM (Sun 16th Aug) | 11ft (3.5m) 11s |
| Most Powerful | 12PM (Sun 16th Aug) | 11ft (3.5m) 11s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let's have a look at what's on the cards for Onjuku over the next couple of weeks.
Overall, it's a bit of a slow burner. The first few days are pretty much a write-off with messy, lumpy conditions. Things start to clean up around the middle of next week, but the real action looks to be a week away with a solid pulse of swell, though you'll need to pick your window carefully.
We kick off with nothing doing. Tuesday the 11th is a complete loss – onshore wind and poor surf. Wednesday the 12th and Thursday the 13th morning offer a glimmer of hope. On Thursday morning the 13th, we’ve got a clean 5-foot easterly swell with a moderate period of 9 seconds and a nice cross-offshore breeze. The combined energy is moderate at 446, so it’s more of a finesse session than a power day.
The real standout, without a doubt, is Monday the 17th. For the morning session, the forecast is glassy – absolute dead calm – with a clean 6-foot easterly swell (9-second period). The combined energy is a solid 514, meaning there’s some decent push behind it. The wind is a light southerly at just 3 mph, so the surface will be like a mirror. This is the best on offer: clean, user-friendly, and no crowds to worry about.
Now, there is a big pulse coming through on Sunday the 16th, with swell heights hitting 12 feet (E direction, 11-second period). The combined energy is massive at over 2600. That’s expert territory – way too big for the average punter – and the forecast even flags it as potentially too big for this break. If you’re a charger and you’re in, Sunday afternoon might be on with a gentle offshore wind, but it’s a serious step up.
After Monday the 17th, it drops off again. The rest of the second week is pretty lean with onshore winds and small, weak swells. The water temp is sitting at a warm 82°F, which is about a couple of degrees above normal for this time of year – lovely for a long session.
So, to sum it up: wait it out. The real sweet spot is Monday morning the 17th. Get on it.
Rusty.
Short Range ForecastHeavy rain (total 80mm), heaviest during Tue night. Warm (max 27°C on Thu morning, min 23°C on Tue night). Winds decreasing (strong winds from the SSW on Tue night, light winds from the N by Wed night). | Days 5-7 Weather SummaryLight rain (total 9mm), mostly falling on Fri night. Warm (max 27°C on Fri afternoon, min 22°C on Sat night). Winds decreasing (fresh winds from the NNW on Sun morning, calm by Sun night). | |||||||||||||||||||
Tue 11 | Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | ||||||||||||||
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) | E 12 | E 11 | ESE 6 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 10 | E 10 | E 10 | E 10 | E 10 | E 11 | ENE 11 | ENE 10 | E 9 | ENE 9 | E 9 |
Wave Graph  | ||||||||||||||||||||
 kJ | 1229 | 514 | 383 | 201 | 320 | 375 | 426 | 434 | 434 | 424 | 646 | 913 | 821 | 1748 | 2469 | 2570 | 1314 | 452 | 307 | 269 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | cross-on | cross | off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | off | cross-off | off | cross-off | glassy | on | cross-on |
High Tide | 4:57PM1.35m | 2:54AM1.44m | 5:21PM1.37m | 3:50AM1.49m | 5:43PM1.38m | 4:40AM1.50m | 6:04PM1.38m | 5:27AM1.47m | 6:24PM1.39m | 6:12AM1.40m | 6:43PM1.39m | 6:57AM1.29m | 7:02PM1.40m | |||||||
Low Tide | 9:44PM0.99m | 10:15AM0.00m | 10:23PM0.88m | 10:54AM0.03m | 11:01PM0.75m | 11:29AM0.11m | 11:38PM0.63m | 12:00PM0.24m | 00:15AM0.53m | 12:27PM0.38m | 00:54AM0.46m | 12:51PM0.53m | 1:34AM0.43m | |||||||
 |  |  | |  | |  | | | | |  | |  | | |  | | |  | |
 | — | — | 4:54 | — | — | 4:56 | — | — | 4:56 | — | — | 4:56 | — | — | 4:58 | — | — | 4:58 | — | — |
 | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:29 | — | — | 6:28 | — | — | 6:27 | — | — | 6:25 | — |
mm | 10 | 48 | 9 | 5 | 2 | 1 | — | 2 | 3 | 1 | 7 | — | — | 1 | — | — | — | — | — | — |
Temp °C | 24 | 23 | 25 | 26 | 25 | 27 | 27 | 25 | 27 | 27 | 25 | 27 | 27 | 23 | 26 | 27 | 25 | 27 | 28 | 26 |
Feels °C | 21 | 19 | 24 | 28 | 29 | 29 | 29 | 27 | 28 | 28 | 27 | 25 | 24 | 20 | 24 | 27 | 26 | 29 | 29 | 28 |
Swell 1 Height (m) Direction Period (s) | E 12 | E 11 | SSW 6 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 10 | E 9 | E 10 | S 10 | E 10 | E 11 | ENE 11 | ENE 10 | E 9 | ENE 9 | E 9 |
| kJ | 1229 | 514 | 29 | 201 | 320 | 375 | 426 | 434 | 434 | 424 | 427 | 669 | 53 | 1131 | 2469 | 2570 | 1314 | 452 | 307 | 269 |
Swell 2 Height (m) Direction Period (s) | S 11 | NNE 10 | S 10 | S 6 | S 6 | S 10 | S 10 | SSW 9 | SSE 11 | S 10 | SSE 9 | SSW 8 | SE 18 | S 10 | SSW 9 | S 11 | SSW 10 | SSW 10 | SSW 9 | SE 10 |
| kJ | 57 | 261 | 53 | 25 | 24 | 71 | 48 | 28 | 49 | 70 | 62 | 14 | 13 | 30 | 16 | 37 | 31 | 32 | 28 | 37 |
Swell 3 Height (m) Direction Period (s) | SE 13 | SW 10 | SE 13 | S 10 | S 10 | — | SE 12 | SSE 12 | S 9 | SSW 9 | SSW 9 | S 11 | SE 10 | SE 18 | S 12 | SE 17 | SE 11 | SE 11 | SE 11 | SSW 9 |
| kJ | 27 | 39 | 6 | 53 | 51 | — | 6 | 27 | 14 | 8 | 16 | 22 | 4 | 12 | 11 | 11 | 30 | 30 | 30 | 25 |
Wind waves Height (m) Direction Period (s) | WSW 3 | S 6 | ESE 6 | ESE 6 | — | — | — | — | — | — | E 10 | E 10 | E 10 | E 10 | NNE 7 | NW 4 | NNE 8 | NW 3 | — | SSW 2 |
| kJ | 8 | 251 | 383 | 77 | — | — | — | — | — | — | 646 | 913 | 821 | 1748 | 738 | 18 | 473 | 4 | — | 1 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 110 | 200 | 74 | 68 | 0 | 0 | 51 | 0 | 51 | 51 | 0 | 206 | 51 | 73 | 45 | 5 | 0 | 0 | 9 | 23 |
Best forecast wave conditions in Chiba | ||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||
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Information about the Onjuku Surf forecast
The above surf forecast table for Onjuku provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Onjuku can be found by selecting the local surf guide option on the grey menu. Our Onjuku 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 (Onjuku) 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 Onjuku 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.
Onjuku is 3 km (2 miles) from Ohara. If you plan a holiday in Chiba, look for hotels and other accommodation in Ohara. Ohara has rooms for a wide range of budgets as well as car hire and transport links.
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