Surf Forecasts:
Onjuku surf forecast from 26 Aug 2026:
- Best quality surf: Thursday 27 Aug, 6PM (local time) - 2.5ft (0.7m), 13s period, E swell with cross-offshore winds.
- Most powerful swell: Thursday 27 Aug, 12PM (local time) - 5ft (1.6m), 11s period, SW swell with 548 kJ wave energy.
- Next surfable swell (1★+): Thursday 27 Aug, 6PM (local time) - 2.5ft (0.7m), 13s 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 Thursday (Aug 27) at 6PM. The primary swell is predicted to be 0.7m and 13s period with a secondary swell of 0.9m and 6s. Another secondary swell of 0.7m and 10s is also forecast. Another secondary swell of 1.2m and 6s is also forecast. 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 1.6m 11s and forecast to arrive on Thursday (Aug 27) at 12PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.8m 4s period and expected on Saturday (Aug 29) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6PM (Thu 27th Aug) | 2.5ft (0.7m) 13s |
| Best Surf | 6PM (Thu 27th Aug) | 2.5ft (0.7m) 13s |
| Most Powerful | 12PM (Thu 27th Aug) | 5ft (1.6m) 11s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
G’day, Rusty here, and I’ve got the goods on Onjuku. Right now, and for the next several days, it’s a bit of a tough slog—nothing’s really happening. The first surf worth paddling out for doesn’t show up until Tuesday morning, September 1st, so you’ve got a gap of a few days where you’re better off checking the wax, not the water.
Tuesday, September 1st is the first real standout. Tuesday morning, the wind swings around to a light NNE breeze, coming cross-offshore, and that’s gonna keep the surface clean. The swell is pushing in from the south at 3ft, with a solid 13-second period—proper groundswell energy that’ll give you some long, lined-up waves. The combined energy is moderate at 517, enough to get you into something fun. This is a spread-out beach break, so with that longer period, it might not wall up perfectly, but the conditions should be sweet. Water temp is about average for this time of year, so no surprises there.
Now, if you’re looking further ahead, Thursday, September 10th is the one to circle. Thursday morning, the swell jumps to 6ft from the south with a 14-second period—that’s a very long period groundswell, proper energy. The combined energy is strong at 1398. The wind is a clean cross-off from the northeast at 16 mph, so the surface will be glassy and inviting. That size is getting into expert territory—over 5ft, so it’s not for beginners. Thursday afternoon eases a touch to 5ft, but still clean and long-period. Friday the 11th morning also looks promising, with 4ft, a 13-second period, and a light cross-off breeze. That’s a solid session for the more experienced crew.
The rest of the window is a write-off—windy, onshore, or just too small and messy. Onjuku is inconsistent, and this stretch proves it. But when it does fire, like on the 1st and the 10th, it’s worth the wait.
Rusty.
Short Range ForecastModerate rain (total 15mm), heaviest on Thu morning. Warm (max 29°C on Thu morning, min 24°C on Thu afternoon). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 9mm), mostly falling on Tue night. Warm (max 28°C on Mon morning, min 25°C on Sun night). Wind will be generally light. | ||||||||||||||||||||
Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | Monday 31 | Tuesday 1 | Wednesday 2 | |||||||||||||||
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) | SW 6 | SW 6 | E 13 | E 12 | SW 6 | E 12 | E 11 | E 11 | E 11 | E 11 | E 11 | E 11 | S 13 | S 12 | S 11 | ESE 11 | ESE 11 | S 11 | S 11 | S 11 | S 11 |
Wave Graph  | |||||||||||||||||||||
 kJ | 98 | 173 | 163 | 151 | 132 | 99 | 94 | 63 | 58 | 59 | 61 | 56 | 85 | 184 | 224 | 180 | 217 | 303 | 233 | 229 | 224 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-on | cross | on | cross | cross-off | cross-off | cross-off | glassy | cross-on | glassy | cross-on | cross-on | cross-on | cross | cross-on | cross-on | on | on | on |
High Tide | 4:57PM1.33m | 3:58AM1.42m | 5:14PM1.37m | 4:38AM1.44m | 5:32PM1.40m | 5:17AM1.43m | 5:51PM1.42m | 5:58AM1.39m | 6:10PM1.43m | 6:41AM1.32m | 6:31PM1.44m | 7:30AM1.23m | 6:53PM1.43m | ||||||||
Low Tide | 10:12AM0.19m | 10:21PM0.74m | 10:41AM0.20m | 10:51PM0.63m | 11:09AM0.24m | 11:22PM0.53m | 11:35AM0.32m | 11:54PM0.43m | 12:02PM0.43m | 00:30AM0.36m | 12:27PM0.56m | 1:09AM0.32m | 12:52PM0.70m | 1:54AM0.31m | |||||||
 | |  | |  |  | |  | | | | | |  |  | | |  | |  | | |
 | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — | 5:07 | — | — | 5:09 | — | — | 5:09 | — | — | 5:11 | — | — |
 | — | 6:13 | — | — | 6:12 | — | — | 6:09 | — | — | 6:08 | — | — | 6:07 | — | — | 6:06 | — | — | 6:05 | — |
mm | 6 | 6 | 2 | 1 | — | — | — | — | — | — | — | — | 1 | — | 2 | 1 | 1 | 4 | 5 | 1 | 3 |
Temp °C | 29 | 28 | 27 | 28 | 29 | 26 | 27 | 26 | 25 | 26 | 27 | 26 | 28 | 28 | 26 | 28 | 28 | 26 | 28 | 28 | 26 |
Feels °C | 31 | 30 | 28 | 33 | 32 | 30 | 28 | 27 | 26 | 31 | 31 | 30 | 31 | 29 | 30 | 32 | 31 | 29 | 30 | 29 | 28 |
Swell 1 Height (m) Direction Period (s) | SSW 6 | SSW 6 | E 13 | SSW 6 | SSW 6 | SSW 7 | E 11 | E 11 | ENE 4 | E 11 | SSW 5 | SSW 6 | S 13 | S 12 | S 11 | S 10 | S 10 | S 11 | S 11 | S 11 | S 11 |
| kJ | 56 | 62 | 163 | 60 | 41 | 71 | 94 | 63 | 12 | 59 | 34 | 18 | 85 | 184 | 224 | 172 | 162 | 303 | 233 | 229 | 224 |
Swell 2 Height (m) Direction Period (s) | SSE 10 | E 13 | S 9 | E 12 | E 12 | E 12 | SSW 6 | SSW 8 | E 11 | ENE 5 | E 11 | E 11 | SSW 5 | NE 7 | NE 7 | ESE 11 | ESE 11 | ESE 11 | E 11 | E 11 | E 10 |
| kJ | 94 | 173 | 85 | 151 | 103 | 99 | 12 | 19 | 58 | 7 | 61 | 56 | 13 | 31 | 25 | 180 | 217 | 205 | 229 | 182 | 123 |
Swell 3 Height (m) Direction Period (s) | E 11 | SSE 10 | SSW 6 | S 8 | S 8 | SE 9 | SE 11 | SSE 11 | SE 10 | SE 10 | ENE 5 | ENE 5 | E 11 | E 10 | ESE 12 | NE 7 | ENE 8 | NE 8 | SE 10 | SE 9 | SE 10 |
| kJ | 59 | 80 | 27 | 35 | 33 | 23 | 30 | 47 | 27 | 26 | 8 | 9 | 37 | 35 | 58 | 27 | 37 | 55 | 26 | 23 | 24 |
Wind waves Height (m) Direction Period (s) | SW 6 | SW 6 | — | SW 6 | SW 6 | — | ENE 3 | ENE 5 | — | — | — | NE 4 | SW 5 | SW 4 | SW 5 | — | — | — | — | — | — |
| kJ | 98 | 150 | — | 120 | 132 | — | 8 | 28 | — | — | — | 8 | 28 | 13 | 4 | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 101 | 18 | 18 | 9 | 9 | 9 | 0 | 56 | 103 | 5 | 0 | 23 | 2 | 51 | 51 | 0 | 0 | 9 | 9 | 9 | 9 |
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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