Surf Forecasts:
Onjuku surf forecast from 27 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 3 Sep, 12PM (local time) - 5ft (1.6m), 12s period, S swell with 678 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 1.0m and 6s. Another secondary swell of 1.3m 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 12s and forecast to arrive on Thursday (Sep 03) at 12PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 5s period and expected on Saturday (Aug 29) at 3PM.
| 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 3rd Sep) | 5ft (1.6m) 12s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here, let’s talk about what’s on the table for the next couple of weeks.
We’re looking at a pretty quiet start, but don’t write it off just yet. The water is sitting at 82°F at Onjuku, which is a touch warmer than normal for this time of year, so you can leave the thick steamer at home.
The first few days are a bit of a write-off. Thursday the 27th kicks off with messy cross-onshore winds and weak, choppy surf – not worth paddling out for. Friday the 28th isn’t much better, with a bumpy wind swell swinging in from the SW around 5ft, but the period is a short 6 seconds, so it’s all chop and no shape. Saturday and Sunday the 30th are tiny, with only 2ft on offer, though Sunday morning does see a little clean-up with a light cross-offshore breeze.
Monday the 31st is where things start to look up. The morning is still small, but by the afternoon we get a clean 2ft swell from the south with light offshore winds. The wave energy is moderate (242) and the conditions are clean. It’s not a standout, but it’s a solid sign of life.
The real standout window opens on Friday the 4th of September. After a rough morning with strong onshore winds and a messy 8ft swell, the afternoon flips completely. The wind swings to a light cross-offshore from the NW, and the swell settles to 8ft from the SSE, clean and powerful. The wave energy is strong (1197) and the rating is excellent for experienced surfers. This is the one to circle. It’s too big for beginners, but if you’ve got the skills, this is the best session of the forecast.
After that, we get a few days of solid, clean conditions but with average wave quality. Saturday the 5th and Sunday the 6th hold 6ft to 8ft swell from the SSE and S, with clean offshore winds, but the surf is marginal due to tide or swell shape. Not a write-off, but not the standout.
The next true highlight lands on Tuesday the 8th of September. The morning is glassy, with zero wind and a clean 7ft swell from the south. The wave energy is strong (1180) and the conditions are described as excellent for experienced surfers. This is another top-tier session, but again, it’s big and best left to the crew who know what they’re doing.
After that, the wind turns ugly. From Wednesday the 9th through to Friday the 11th, we’re looking at strong onshore winds, messy cross-onshore conditions, and dropping swell quality. The waves are still around 5ft to 8ft, but the wind is chewing them up. It’s a frustrating end to the run.
So, bottom line: if you’re keen, target the afternoon of Friday the 4th of September and the glassy morning of Tuesday the 8th of September. Those are your two best shots. The rest is either too small, too windy, or just average.
Rusty.
Short Range ForecastLight rain (total 2mm), mostly falling on Thu afternoon. Warm (max 29°C on Thu afternoon, min 23°C on Sat night). Winds decreasing (fresh winds from the SW on Thu afternoon, calm by Fri morning). | Days 5-7 Weather SummaryLight rain (total 6mm), mostly falling on Tue morning. Warm (max 29°C on Mon morning, min 24°C on Sun afternoon). Wind will be generally light. | |||||||||||||||||||
Thu 27 | Friday 28 | Saturday 29 | Sunday 30 | Monday 31 | Tuesday 1 | Wednesday 2 | ||||||||||||||
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 13 | E 13 | E 12 | E 12 | E 12 | E 12 | E 11 | E 11 | E 11 | E 11 | E 11 | E 11 | S 10 | S 10 | ESE 11 | ESE 11 | E 12 | S 10 | S 10 | SSW 10 |
Wave Graph | ||||||||||||||||||||
173 | 163 | 151 | 103 | 99 | 96 | 60 | 58 | 62 | 61 | 56 | 56 | 78 | 125 | 173 | 158 | 262 | 252 | 247 | 370 | |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-off | cross-on | cross | cross-off | cross | off | cross-off | cross | glassy | cross-on | on | on | on | on | 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 | 10:21PM0.74m | 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 | |||||||
— | — | 5:07 | — | — | 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 | 1 | — | — | 1 | — | — | — | — | — | — | — | — | — | — | 2 | — | 3 | 1 | — | 1 |
Temp °C | 29 | 27 | 28 | 28 | 26 | 27 | 26 | 26 | 25 | 25 | 26 | 29 | 29 | 26 | 28 | 28 | 27 | 28 | 28 | 27 |
Feels °C | 29 | 28 | 33 | 32 | 29 | 28 | 28 | 31 | 28 | 28 | 29 | 30 | 30 | 29 | 31 | 30 | 31 | 29 | 30 | 28 |
Swell 1 Height (m) Direction Period (s) | E 13 | S 9 | SSW 6 | SSW 6 | SSW 8 | E 12 | E 11 | ENE 5 | E 11 | E 11 | E 11 | NE 7 | S 10 | S 10 | ESE 11 | ESE 11 | E 12 | S 10 | E 10 | S 10 |
173 | 83 | 58 | 44 | 60 | 96 | 60 | 21 | 62 | 61 | 56 | 25 | 78 | 125 | 173 | 158 | 262 | 252 | 138 | 247 | |
Swell 2 Height (m) Direction Period (s) | SSE 10 | E 13 | E 12 | E 12 | E 12 | S 8 | SSE 11 | E 11 | NE 5 | SSW 6 | NE 6 | E 11 | NE 7 | ESE 12 | S 10 | S 9 | S 9 | E 11 | SE 10 | E 10 |
58 | 163 | 151 | 103 | 99 | 31 | 47 | 58 | 13 | 13 | 19 | 56 | 24 | 98 | 118 | 106 | 106 | 184 | 16 | 122 | |
Swell 3 Height (m) Direction Period (s) | S 11 | SE 10 | S 8 | S 8 | SE 9 | SE 11 | SSW 8 | SE 10 | SE 10 | SE 10 | SE 10 | S 12 | E 11 | NE 7 | NE 7 | NE 8 | S 11 | SSE 10 | S 15 | SE 10 |
56 | 26 | 35 | 33 | 23 | 30 | 19 | 27 | 26 | 26 | 26 | 41 | 35 | 23 | 23 | 28 | 40 | 10 | 4 | 16 | |
Wind waves Height (m) Direction Period (s) | SSW 5 | SW 6 | SW 6 | — | — | NE 3 | NE 5 | — | — | NE 6 | — | SSW 5 | SSW 4 | — | — | — | — | — | S 10 | SSW 10 |
66 | 32 | 95 | — | — | 4 | 64 | — | — | 15 | — | 12 | 11 | — | — | — | — | — | 247 | 370 | |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 15 | 15 | 9 | 2 | 9 | 103 | 536 | 56 | 0 | 0 | 9 | 2 | 0 | 0 | 16 | 51 | 51 | 9 | 9 | 964 |
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.











