Surf Forecasts:
Onjuku surf forecast from 29 Aug 2026:
- Best quality surf: Tuesday 1 Sep, 3AM (local time) - 3ft (0.9m), 12s period, ESE swell with cross-offshore winds.
- Most powerful swell: Sunday 6 Sep, 12AM (local time) - 6ft (1.8m), 7s period, ENE swell with 337 kJ wave energy.
- Next surfable swell (1★+): Sunday 30 Aug, 6AM (local time) - 1.5ft (0.5m), 11s 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 Sunday (Aug 30) at 6AM. The primary swell is predicted to be 0.5m and 11s period with a secondary swell of 0.4m and 7s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 1.8m 7s and forecast to arrive on Sunday (Sep 06) 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 1.3m 5s period and expected on Friday (Sep 04) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Sun 30th Aug) | 1.5ft (0.5m) 11s |
| Best Surf | 3AM (Tue 1st Sep) | 3ft (0.9m) 12s |
| Most Powerful | 12AM (Sun 6th Sep) | 6ft (1.8m) 7s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, mates, let’s break it down. The surf around here is pretty quiet at first, but there’s a big window of solid waves coming if you know what you’re doing.
Onjuku (Chiba) is the only spot worth talking about. The first few days are dead—Sunday the 30th and Monday the 31st have tiny, weak swell with clean but useless conditions.
Things improve Tuesday morning, September 1st. You’ll see clean 3ft ESE swell with a 12-second period and moderate energy (315). The wind is light and cross-off, so the waves will be clean. It’s inconsistent here, so you’ll wait for sets. Wednesday morning the 2nd is similar: 3ft, 10-second ESE swell with clean conditions and a light breeze. Fun little waves.
Then Thursday and Friday are messy with onshore wind and chop. Not worth it.
The real show starts Sunday, September 6th. Swell jumps to 6ft from the east with 8-second period. Combined energy is strong (562), and the wind stays clean and cross-off. The short period means it’ll be a bit fat and weak at the beach, but a point or reef could work. Monday the 7th holds similar.
The standout stretch begins Tuesday, September 8th. Morning sees 8ft SE swell with a 10-second period and massive energy (1309)—this is big, powerful groundswell. Wind is light and cross-off, so the surf will be clean and lined up. But at over 8ft, this is experts-only. Beginners stay on the beach. The swell direction (SE) is a perfect match for the optimum SSE.
Wednesday the 9th still has 7ft to 8ft swell and strong energy, but the wind picks up—fresh to moderate cross-off—so it stays clean but gets harder. Thursday the 10th is another standout: 8ft SE swell with a 12-second period, very long period groundswell. The combined energy is a huge 2044. Wind is strong offshore from the NNE at 28 mph, making for clean, hollow waves—but paddling in will be brutal. For the hardcore only.
Friday the 11th gets messy with strong cross-shore winds and lumpy conditions. The weekend is blown out by near gale onshore slop.
Finally, Monday, September 14th offers a nice change: 4ft SSW swell with a 13-second period, moderate energy (614), and clean cross-off winds. The swell is from the SSW, not the optimum SSE, but it’s long-period and will offer good shape. Much more manageable for intermediates.
Best on offer: Tuesday, September 8th morning is the clear winner—big, clean, powerful SE groundswell with light winds. Thursday, September 10th morning is the other standout for the brave and strong paddlers with that strong offshore wind.
- Rusty
Short Range ForecastLight rain (total 5mm), mostly falling on Sat night. Warm (max 27°C on Tue morning, min 22°C on Sat night). Wind will be generally light. | Days 5-7 Weather SummaryModerate rain (total 12mm), heaviest on Thu night. Warm (max 28°C on Wed afternoon, min 22°C on Thu night). Winds increasing (light winds from the NE on Wed morning, fresh winds from the ENE by Thu night). | ||||||||||||||||||
Sunday 30 | Monday 31 | Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | ||||||||||||||
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 11 | E 11 | E 11 | E 11 | SE 14 | ESE 14 | ESE 12 | ESE 12 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | ESE 12 | E 11 | E 10 | S 6 | ENE 6 | ENE 7 | ENE 6 |
Wave Graph  | |||||||||||||||||||
 kJ | 58 | 59 | 60 | 56 | 56 | 73 | 175 | 237 | 173 | 183 | 118 | 111 | 192 | 116 | 78 | 108 | 115 | 107 | 160 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | cross-off | cross-off | off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | on | on | cross-on | cross-on | cross-off | cross-off | cross-off | cross-off |
High Tide | 5:17AM1.43m | 5:51PM1.42m | 5:58AM1.39m | 6:10PM1.43m | 6:41AM1.32m | 6:31PM1.44m | 7:30AM1.23m | 6:53PM1.43m | 8:31AM1.12m | 7:17PM1.40m | 10:14AM1.02m | 7:46PM1.36m | |||||||
Low Tide | 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 | 1:12PM0.84m | 2:52AM0.34m | 1:18PM0.97m | |||||||
 |  | | |  | |  | |  | | | |  |  |  |  |  | | | |
 | — | 5:07 | — | — | 5:09 | — | — | 5:09 | — | — | 5:11 | — | — | 5:11 | — | — | 5:11 | — | — |
 | 6:09 | — | 6:08 | — | — | 6:07 | — | — | 6:06 | — | — | 6:05 | — | — | 6:04 | — | — | 6:01 | — |
mm | 1 | — | — | 1 | 2 | 1 | — | — | — | — | — | — | 2 | 1 | 1 | 8 | — | — | — |
Temp °C | 23 | 25 | 25 | 25 | 26 | 26 | 25 | 27 | 27 | 25 | 27 | 28 | 27 | 26 | 28 | 23 | 24 | 25 | 24 |
Feels °C | 25 | 26 | 27 | 28 | 28 | 28 | 27 | 30 | 30 | 29 | 31 | 31 | 30 | 29 | 30 | 22 | 25 | 24 | 23 |
Swell 1 Height (m) Direction Period (s) | E 11 | E 11 | E 11 | E 5 | E 11 | ESE 14 | ENE 7 | ESE 12 | E 7 | E 7 | E 7 | ESE 7 | SE 6 | SE 6 | SE 6 | S 6 | E 10 | E 9 | ESE 9 |
| kJ | 58 | 59 | 60 | 18 | 56 | 73 | 73 | 237 | 109 | 131 | 103 | 108 | 113 | 101 | 66 | 108 | 49 | 44 | 28 |
Swell 2 Height (m) Direction Period (s) | SE 10 | SSW 7 | SSW 7 | E 11 | SE 9 | E 11 | ESE 12 | ENE 7 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | ESE 12 | E 11 | E 10 | E 10 | SSW 8 | SE 6 | SE 9 |
| kJ | 27 | 20 | 18 | 56 | 23 | 56 | 175 | 64 | 173 | 183 | 118 | 111 | 192 | 116 | 78 | 71 | 22 | 15 | 12 |
Swell 3 Height (m) Direction Period (s) | SSW 5 | SE 10 | SE 10 | SSW 7 | SE 14 | SE 9 | E 11 | SSW 8 | SSW 9 | SSW 8 | SSW 8 | SSW 8 | SSW 8 | SSW 8 | SE 10 | SE 10 | SE 6 | SSW 9 | SSW 11 |
| kJ | 5 | 25 | 26 | 17 | 51 | 22 | 36 | 14 | 15 | 14 | 23 | 22 | 22 | 21 | 24 | 23 | 19 | 25 | 12 |
Wind waves Height (m) Direction Period (s) | ENE 5 | ENE 5 | E 5 | — | ENE 6 | ENE 6 | NE 7 | NNE 7 | NNE 8 | — | — | — | — | SSW 5 | SSW 8 | — | ENE 6 | ENE 7 | ENE 6 |
| kJ | 22 | 28 | 25 | — | 40 | 60 | 93 | 25 | 34 | — | — | — | — | 28 | 60 | — | 115 | 107 | 160 |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 0 | 22 | 16 | 0 | 12 | 56 | 12 | 0 | 51 | 0 | 0 | 9 | 9 | 135 | 143 | 200 | 51 | 51 | 51 |
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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