Surf Forecasts:
Onjuku surf forecast from 9 Sep 2026:
- Best quality surf: Friday 11 Sep, 12AM (local time) - 5.5ft (1.7m), 7s period, ENE swell with offshore winds.
- Most powerful swell: Thursday 10 Sep, 12AM (local time) - 5.5ft (1.7m), 9s period, S swell with 450 kJ wave energy.
- Next surfable swell (1★+): Friday 11 Sep, 12AM (local time) - 5.5ft (1.7m), 7s period with ENE 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 Friday (Sep 11) at 12AM. The primary swell is predicted to be 1.7m and 7s period with a secondary swell of 1.4m and 7s. Another secondary swell of 0.7m and 8s is also forecast. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 1.7m 9s and forecast to arrive on Thursday (Sep 10) at 12AM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.9m 7s period and expected on Friday (Sep 11) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12AM (Fri 11th Sep) | 5.5ft (1.7m) 7s |
| Best Surf | 12AM (Fri 11th Sep) | 5.5ft (1.7m) 7s |
| Most Powerful | 12AM (Thu 10th Sep) | 5.5ft (1.7m) 9s |
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 Onjuku has in store for us over the next couple of weeks.
Honestly, the first week and a bit is a tough watch. We’ve got a few pulses of swell, but the conditions are a dog’s breakfast – onshore winds, sloppy texture, and just a general lack of quality. There’s basically nothing worth paddling out for until we hit the second week, with a gap of several days of poor surf ahead.
The real standout, and I mean the *only* one worth getting genuinely excited about, lands on Sunday, 20th of September in the morning. This is the big one. We’re looking at a solid 8ft swell out of the SSE, and it’s packing serious grunt with a 16-second period. That is proper long-period groundswell. The combined wave energy is absolutely pumping at 2958 – that’s some serious power. What makes this special is the NNE wind blowing at just 6 mph, keeping the surface glassy and clean. This is excellent surf, but listen, at this size and with that period, it’s strictly for experienced surfers. The waves are going to be chunky and powerful, best handled on a proper reef or point setup.
The morning after, on Monday the 21st, the swell keeps building, hitting 12ft from the SSE with a 16-second interval. The energy goes through the roof (6424). But that’s the problem – it’s too much for Onjuku. The wind is also onshore. That system looks like it gets completely out of control, with 25ft monsters forecast by Wednesday the 23rd and hurricane-force winds. Save your energy for those quality windows, because most of this is a write-off. A bit later, on Thursday the 24th, we get a drop back to 10ft from the S, but with a strong offshore NNE wind at 19 mph. That could be a very clean, challenging session for those who know what they’re doing.
For the rest, you’ll see a few small windows of clean surf with small, long-period E swells (like on Friday the 11th and Sunday the 13th), but the wave heights are tiny at 2ft to 3ft and the combined energy is weak. Not worth rushing for.
So, save your board wax for that Sunday the 20th morning session. That’s the pick of the forecast by a long shot.
Rusty.
Short Range ForecastHeavy rain (total 32mm), heaviest during Wed night. Warm (max 24°C on Sat afternoon, min 19°C on Wed night). Mainly fresh winds. | Days 5-7 Weather SummaryLight rain (total 7mm), mostly falling on Mon night. Warm (max 28°C on Tue morning, min 22°C on Sat night). Wind will be generally light. | ||||||||||||||||||
Thursday 10 | Friday 11 | Saturday 12 | Sunday 13 | Monday 14 | Tuesday 15 | ||||||||||||||
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) | S 9 | NE 7 | ENE 7 | ENE 7 | E 14 | E 14 | E 14 | E 14 | E 13 | E 13 | SE 9 | SE 9 | SE 9 | SE 9 | SE 9 | SE 8 | SE 8 | E 14 | E 13 |
Wave Graph  | |||||||||||||||||||
 kJ | 450 | 244 | 249 | 266 | 106 | 101 | 136 | 134 | 128 | 128 | 101 | 132 | 152 | 179 | 235 | 232 | 210 | 200 | 167 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | cross-off | off | off | off | off | cross-off | cross-off | off | cross-off | cross-on | on | on | on | on | cross-on | cross-on | glassy |
High Tide | 3:06AM1.40m | 4:32PM1.36m | 3:56AM1.45m | 4:50PM1.39m | 4:41AM1.47m | 5:08PM1.41m | 5:24AM1.44m | 5:26PM1.43m | 6:04AM1.38m | 5:44PM1.44m | 6:45AM1.29m | 6:03PM1.43m | |||||||
Low Tide | 9:34PM0.80m | 9:55AM0.18m | 10:07PM0.64m | 10:29AM0.24m | 10:40PM0.50m | 10:59AM0.34m | 11:13PM0.38m | 11:26AM0.45m | 11:46PM0.30m | 11:50AM0.57m | 00:19AM0.26m | 12:11PM0.69m | 00:53AM0.27m | ||||||
 |  | |  |  | | | | |  |  |  |  | | | |  | | | |
 | — | 5:16 | — | — | 5:16 | — | — | 5:18 | — | — | 5:18 | — | — | 5:18 | — | — | 5:20 | — | — |
 | — | — | 5:53 | — | — | 5:52 | — | — | 5:51 | — | — | 5:49 | — | — | 5:47 | — | — | 5:46 | — |
mm | 20 | 2 | 2 | 4 | — | 2 | 1 | — | 1 | — | — | — | 2 | — | — | 4 | 1 | — | 3 |
Temp °C | 22 | 21 | 22 | 20 | 20 | 20 | 21 | 23 | 24 | 23 | 25 | 26 | 26 | 27 | 27 | 25 | 28 | 27 | 25 |
Feels °C | 21 | 19 | 20 | 18 | 20 | 20 | 22 | 24 | 26 | 25 | 29 | 30 | 29 | 28 | 28 | 27 | 29 | 30 | 31 |
Swell 1 Height (m) Direction Period (s) | S 9 | S 8 | S 8 | ENE 7 | ENE 6 | S 8 | E 14 | E 14 | E 13 | E 13 | SE 9 | SE 9 | SE 9 | SE 9 | SE 9 | SE 8 | SE 8 | SE 8 | SE 8 |
| kJ | 450 | 199 | 107 | 192 | 37 | 40 | 136 | 134 | 128 | 128 | 101 | 132 | 152 | 179 | 235 | 232 | 210 | 177 | 167 |
Swell 2 Height (m) Direction Period (s) | ESE 16 | ESE 15 | ESE 15 | S 8 | S 8 | E 14 | S 8 | SE 9 | SE 9 | NE 6 | E 13 | E 13 | E 12 | E 12 | E 12 | E 14 | E 14 | E 14 | E 13 |
| kJ | 49 | 42 | 72 | 63 | 41 | 101 | 28 | 40 | 39 | 30 | 86 | 125 | 76 | 76 | 78 | 187 | 189 | 200 | 167 |
Swell 3 Height (m) Direction Period (s) | ESE 11 | SE 11 | SE 11 | ESE 14 | E 14 | SE 10 | SE 9 | SSW 7 | SSW 7 | SE 8 | ENE 6 | NE 6 | NE 7 | NE 6 | ENE 6 | NE 7 | NE 10 | ENE 10 | ENE 9 |
| kJ | 22 | 18 | 18 | 67 | 106 | 23 | 21 | 18 | 18 | 35 | 16 | 10 | 11 | 10 | 8 | 2 | 4 | 19 | 31 |
Wind waves Height (m) Direction Period (s) | NE 6 | NE 7 | ENE 7 | ENE 7 | NE 7 | NE 6 | NE 5 | NE 6 | NE 6 | — | NE 6 | — | — | S 7 | S 7 | — | — | — | — |
| kJ | 219 | 244 | 249 | 266 | 47 | 36 | 27 | 42 | 33 | — | 25 | — | — | 1 | 1 | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 206 | 51 | 51 | 0 | 0 | 0 | 0 | 16 | 16 | 0 | 0 | 9 | 9 | 9 | 9 | 9 | 110 | 17 | 0 |
Best forecast wave conditions in Chiba | |||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||
Header Global | |||||||||||||||||||
- Map Icons:
Break
Live Wave Height (m)
Live Wind Speed (km/h)
Surf Rating (10 Max)
Ocean Swells (m)- Wind Speed (km/h)
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 Onjuku 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.
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.
Nearest