Surf Forecasts:
Onjuku surf forecast from 1 Sep 2026:
- Best quality surf: Tuesday 8 Sep, 6AM (local time) - 10ft (3.0m), 10s period, SSE swell with glassy winds.
- Most powerful swell: Tuesday 8 Sep, 3PM (local time) - 10ft (3.0m), 11s period, SSE swell with 2,132 kJ wave energy.
- Next surfable swell (1★+): Tuesday 1 Sep, 12PM (local time) - 3ft (0.9m), 12s period with ESE 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 Tuesday (Sep 01) at 12PM. The primary swell is predicted to be 0.9m and 12s period with a secondary swell of 0.9m and 7s. 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 3.0m 11s and forecast to arrive on Tuesday (Sep 08) at 3PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.5m 5s period and expected on Sunday (Sep 06) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12PM (Tue 1st Sep) | 3ft (0.9m) 12s |
| Best Surf | 6AM (Tue 8th Sep) | 10ft (3.0m) 10s |
| Most Powerful | 3PM (Tue 8th Sep) | 10ft (3.0m) 11s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
G’day, Rusty here. Let’s talk about what’s heading our way for Onjuku in the coming days. This 16-day window starts off pretty quiet, with a few clean windows that are worth paddling out for, but you’ve got to pick your moments. We’ll start on Tuesday the 1st of September with some small but fun energy, then work through it. The real standout is the morning of Tuesday the 8th of September, when conditions come together properly – that’s the session to circle on the calendar.
Tuesday morning the 1st of September kicks things off with some clouds and a light ENE wind that’s cross-offshore – that’s clean water right off the bat. Swell is 3ft coming out of the ESE with a period of 12 seconds, so you’ve got a touch of groundswell, not just wind-chop. Combined energy is 314 (moderate), and the water is sitting at 82°, a touch warmer than normal for this time of year. Onjuku is exposed to this direction, and the optimum swell is from the SSE – this is close enough to deliver. It’s not big, but it’s clean, and it’s a fun little start.
Tuesday afternoon stays similar – still 3ft, still clean, wind stays light. Onjuku is inconsistent, so don’t expect bomb sets, but for a small-wave day, this is as good as it gets.
From Wednesday the 2nd through Sunday the 6th of September, conditions go downhill. Onshore winds, cross-chop, some rain and even risk of storms. Swell drops to 2–2ft with short periods around 8 seconds – just weak, messy stuff. The energy dips as low as 58 (weak) by Sunday morning the 6th. I wouldn’t bother with a board those days – it’s mostly blown out or just too small to matter.
Then Monday the 7th of September brings a big shift. The swell jumps to 6ft from the ENE with a very short period of 6 seconds – that’s windswell, not the good stuff – and the combined energy rockets to 444 (moderate). Morning has a strong offshore wind from the NNE at 30 km/h, which cleans it up, but the short period means waves will be lumpy and hard to read. Monday afternoon is better with lighter cross-off wind from the NW and 6ft from the ESE – still short period at 7 seconds, but the texture is clean. It’s a marginal call – you might get a few, but don’t expect quality.
Now the standout: Tuesday the 8th of September, morning. This is the one. Glassy conditions – absolute zero wind – with 8ft swell out of the SSE at 10 seconds. Combined energy is 1412 (strong). That’s proper groundswell, and the period is long enough to hold shape. At 8ft, this is for experienced surfers only – it’s too big for beginners. Onjuku is a beach break, and with that long period, it might break a bit straight, but with glassy conditions, the sandbanks should line up some makeable walls. Crowds can be an issue here sometimes, so get there early.
Tuesday afternoon the 8th gets a bit messier as the wind turns onshore – 10ft from SSE but shorter period and cross-shore chop. Not the same quality.
Wednesday the 9th of September sees huge swell – 13ft in the morning and 12ft in the afternoon, both from the SSE with a 12-second period. Combined energy is off the charts (4710 morning, 3666 afternoon). The forecast says it’s too big for Onjuku – this is a break that can’t handle that much water. Even with cross-off wind, it’ll be a washing machine. Experts only if you’re brave, but I’d give it a miss.
From Thursday the 10th through the end of the window, conditions turn sour with strong onshore winds – up to 31 mph – and messy, blown-out waves. The 15th of September sees a massive 18ft swell with onshores again – a dangerous, ugly combo. By the 16th, it’s still poor with onshore wind and choppy water.
To sum it up: the first two days offer clean small waves, then a handful of quiet days. The real highlight is the glassy morning of Tuesday the 8th of September with 8ft SSE groundswell – get on it if you can handle the size. After that, it’s either too big or too messy. Onjuku doesn’t fire often, but when it does, it reminds you why you surf.
Rusty.
Short Range ForecastModerate rain (total 15mm), heaviest on Thu night. Warm (max 28°C on Thu afternoon, min 22°C on Thu night). Wind will be generally light. | Days 4-6 Weather SummaryHeavy rain (total 217mm), heaviest during Fri afternoon. Warm (max 25°C on Sun night, min 19°C on Fri night). Mainly strong winds. | ||||||||||||||||||||
Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | Saturday 5 | Sunday 6 | Monday 7 | |||||||||||||||
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) | ESE 12 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | E 11 | ESE 10 | E 10 | E 10 | SE 8 | SE 7 | SSW 9 | S 8 | S 8 | ENE 10 | SSE 8 | SE 7 | SE 7 | ENE 6 | ESE 7 | SSE 10 |
Wave Graph | |||||||||||||||||||||
193 | 214 | 210 | 146 | 111 | 235 | 104 | 71 | 68 | 108 | 147 | 99 | 68 | 46 | 51 | 42 | 51 | 89 | 241 | 310 | 746 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | cross-off | cross | cross-on | on | on | cross-on | cross-off | cross-off | cross-off | cross-off | off | cross-off | cross-off | cross-off | cross-off | cross-off | off | cross-off | cross-on |
High Tide | 6:31PM1.44m | 7:30AM1.23m | 6:53PM1.43m | 8:31AM1.12m | 7:17PM1.40m | 10:14AM1.02m | 7:46PM1.36m | 8:26PM1.30m | 4:09PM1.19m | 10:16PM1.23m | 3:44PM1.25m | 00:42AM1.25m | |||||||||
Low Tide | 12:27PM0.56m | 1:09AM0.32m | 12:52PM0.70m | 1:54AM0.31m | 1:12PM0.84m | 2:52AM0.34m | 1:18PM0.97m | 4:13AM0.36m | 6:01AM0.34m | 6:12PM1.19m | 7:30AM0.27m | 8:17PM1.09m | |||||||||
5:09 | — | — | 5:11 | — | — | 5:11 | — | — | 5:11 | — | — | 5:13 | — | — | 5:13 | — | — | 5:13 | — | — | |
— | 6:06 | — | — | 6:05 | — | — | 6:04 | — | — | 6:01 | — | — | 6:00 | — | — | 5:59 | — | — | 5:58 | — | |
mm | — | — | — | — | — | 1 | 3 | 2 | 9 | 18 | 82 | 53 | 4 | 2 | 3 | 3 | 5 | 47 | 13 | 2 | 17 |
Temp °C | 26 | 26 | 25 | 27 | 27 | 26 | 27 | 28 | 24 | 23 | 21 | 20 | 21 | 23 | 24 | 22 | 23 | 25 | 24 | 24 | 24 |
Feels °C | 27 | 28 | 27 | 30 | 29 | 30 | 31 | 31 | 26 | 24 | 18 | 14 | 19 | 19 | 21 | 17 | 21 | 25 | 24 | 26 | 27 |
Swell 1 Height (m) Direction Period (s) | ESE 12 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | E 11 | ESE 10 | S 8 | SE 6 | SE 8 | SE 7 | SSW 9 | S 8 | S 8 | SE 8 | SSE 8 | SE 7 | SE 7 | SE 8 | SSE 9 | SSE 10 |
193 | 214 | 210 | 146 | 111 | 235 | 104 | 51 | 51 | 108 | 147 | 99 | 68 | 46 | 39 | 42 | 51 | 89 | 164 | 66 | 746 | |
Swell 2 Height (m) Direction Period (s) | SSW 8 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | S 8 | S 8 | E 10 | E 10 | S 10 | S 10 | SE 7 | E 9 | SE 8 | ENE 10 | SSW 9 | SSW 9 | SE 11 | S 10 | S 10 | SE 10 |
14 | 59 | 56 | 49 | 37 | 36 | 50 | 71 | 68 | 71 | 47 | 65 | 55 | 45 | 51 | 8 | 8 | 19 | 19 | 64 | 26 | |
Swell 3 Height (m) Direction Period (s) | ESE 15 | SSW 9 | SSW 8 | SSW 8 | SSW 8 | SE 10 | ENE 6 | SE 5 | SSW 8 | E 9 | E 9 | E 7 | SE 7 | ESE 9 | S 8 | ESE 9 | SE 11 | SSW 9 | SE 11 | SE 8 | E 11 |
21 | 15 | 14 | 14 | 23 | 24 | 14 | 13 | 24 | 41 | 40 | 32 | 34 | 26 | 32 | 8 | 5 | 9 | 20 | 15 | 2 | |
Wind waves Height (m) Direction Period (s) | ENE 7 | — | — | — | — | — | — | — | WNW 2 | NE 4 | — | — | — | NE 4 | ENE 5 | ENE 5 | ENE 6 | ENE 6 | ENE 6 | ESE 7 | E 7 |
86 | — | — | — | — | — | — | — | 1 | 3 | — | — | — | 10 | 48 | 125 | 141 | 131 | 241 | 310 | 131 | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 0 | 0 | 0 | 56 | 9 | 9 | 9 | 9 | 2 | 0 | 200 | 206 | 81 | 1543 | 617 | 536 | 536 | 295 | 200 | 0 | 2 |
Best forecast wave conditions in Chiba | |||||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||||
Header Global | |||||||||||||||||||||
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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.











