Surf Forecasts:
Onjuku surf forecast from 25 Aug 2026:
- Best quality surf: Tuesday 1 Sep, 9AM (local time) - 2.5ft (0.7m), 16s period, S swell with cross-offshore winds.
- Most powerful swell: Tuesday 1 Sep, 3PM (local time) - 3.5ft (1.0m), 14s period, S swell with 395 kJ wave energy.
- Next surfable swell (1★+): Thursday 27 Aug, 9AM (local time) - 4.5ft (1.3m), 6s period with SW 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 9AM. The primary swell is predicted to be 1.3m and 6s period with a secondary swell of 0.9m and 6s. Another secondary swell of 0.7m and 10s 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 1.0m 14s and forecast to arrive on Tuesday (Sep 01) at 3PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 5s period and expected on Saturday (Aug 29) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Thu 27th Aug) | 4.5ft (1.3m) 6s |
| Best Surf | 9AM (Tue 1st Sep) | 2.5ft (0.7m) 16s |
| Most Powerful | 3PM (Tue 1st Sep) | 3.5ft (1.0m) 14s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Rusty here. Let's have a look at what Onjuku's got cooking.
We're in a bit of a slow patch right now. The first few days are junked up with choppy cross-onshore winds and weak, sloppy surf. No need to rush out.
The first chance you'll want to paddle out is on Thursday the 27th. For the early morning, we've got clean glass with an offshore breeze and a 4ft swell from the SW. It's short-period, only 6 seconds, so it'll be a bit soft and crumbly, but at least it's clean.
The real highlight is Tuesday the 1st of September. That morning, a clean 2ft south swell rolls in with a very long 16-second period – that's proper groundswell. The combined energy is moderate at 557, and with a light cross-offshore wind, those waves will have some real push and shape. At a beach break like this, a long-period swell can break a bit straight, but the quality will be well above anything else around. Expect some company, as this spot gets busy.
We get a bit of a lull again, but Saturday the 5th of September afternoon shows a 4ft swell from the ENE, though with a short 7-second period. Conditions are clean with a cross-offshore breeze, so it's rideable, just not amazing.
Now, for the heavy stuff. From the 6th to the 9th of September, the swell cranks up. The combined energy goes through the roof, hitting four and five-digit values (up to 2,498), meaning very strong wave energy. Swell heights jump from 5ft up to 8ft from the SSE. At Onjuku, anything over 8ft is expert-only, and with these sizes, it'll be a serious paddle and a heavy drop. The wind stays cross-offshore, keeping the faces clean. This is a long-range outlook, so it's promising but not a guarantee. This is the best bet for experienced surfers looking for a challenge.
So, to sum it up: for clean, quality waves, mark Tuesday the 1st of September. For big-wave action and a real test of nerve, keep an eye on the 7th through the 9th.
Rusty.
Short Range ForecastModerate rain (total 17mm), heaviest on Thu morning. Warm (max 30°C on Wed morning, min 24°C on Thu afternoon). Winds decreasing (fresh winds from the SW on Wed night, calm by Thu afternoon). | Days 5-7 Weather SummaryLight rain (total 9mm), mostly falling on Fri night. Warm (max 28°C on Fri afternoon, min 23°C on Sun night). Wind will be generally light. | |||||||||||||||||||
Tue 25 | Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | Monday 31 | ||||||||||||||
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) | SSE 12 | S 12 | SSE 10 | SSE 9 | SSE 9 | SW 6 | E 13 | E 13 | E 12 | E 12 | E 12 | E 12 | E 11 | E 11 | E 11 | E 12 | E 11 | ENE 7 | SSE 12 | SSE 11 |
Wave Graph  | ||||||||||||||||||||
 kJ | 658 | 287 | 159 | 146 | 115 | 100 | 173 | 168 | 148 | 117 | 99 | 67 | 60 | 58 | 58 | 67 | 61 | 59 | 192 | 198 |
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-on | off | off | cross-on | cross | cross-on | glassy | cross-off | cross-off | cross-off | cross-off | cross-on | cross-off | off | on | off |
High Tide | 4:27PM1.25m | 2:31AM1.30m | 4:41PM1.29m | 3:17AM1.37m | 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 | |||||||
Low Tide | 9:22PM0.95m | 9:42AM0.22m | 9:51PM0.85m | 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 | |||||||
 |  |  | |  |  |  |  |  | | | | |  |  | | | | | | |
 | — | — | 5:05 | — | — | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — | 5:07 | — | — | 5:09 | — | — |
 | 6:15 | — | — | 6:14 | — | — | 6:13 | — | — | 6:12 | — | — | 6:09 | — | — | 6:08 | — | — | 6:07 | — |
mm | — | — | — | — | 1 | 11 | 3 | 2 | — | — | 4 | 3 | — | — | 1 | 1 | — | — | — | — |
Temp °C | 29 | 27 | 30 | 29 | 27 | 27 | 24 | 26 | 28 | 28 | 26 | 24 | 24 | 25 | 26 | 26 | 25 | 26 | 27 | 26 |
Feels °C | 29 | 28 | 31 | 30 | 28 | 31 | 27 | 27 | 28 | 28 | 30 | 24 | 24 | 26 | 28 | 29 | 29 | 30 | 31 | 31 |
Swell 1 Height (m) Direction Period (s) | SSE 12 | SSE 10 | SSE 10 | SSE 9 | SSE 9 | SSW 6 | E 13 | E 13 | E 12 | E 12 | SSW 6 | SSW 7 | E 11 | E 11 | E 11 | ENE 6 | ENE 6 | ENE 7 | SSE 12 | SSE 11 |
| kJ | 658 | 198 | 159 | 146 | 115 | 53 | 173 | 163 | 148 | 103 | 59 | 42 | 60 | 58 | 58 | 40 | 44 | 57 | 192 | 198 |
Swell 2 Height (m) Direction Period (s) | ESE 13 | S 12 | SSW 6 | ESE 12 | E 12 | SSE 10 | SSE 10 | SE 10 | S 9 | SE 9 | E 12 | E 12 | S 7 | SSW 8 | SE 10 | E 12 | E 11 | E 11 | ENE 7 | ENE 7 |
| kJ | 181 | 287 | 39 | 113 | 70 | 94 | 90 | 26 | 36 | 21 | 99 | 67 | 28 | 19 | 25 | 67 | 61 | 59 | 46 | 46 |
Swell 3 Height (m) Direction Period (s) | — | ESE 13 | S 12 | S 12 | SSW 11 | E 11 | S 11 | SSW 10 | SSE 9 | SE 15 | SE 9 | SE 11 | SE 11 | SE 10 | SSW 8 | SSW 7 | SSW 7 | SSW 8 | E 11 | E 11 |
| kJ | — | 176 | 101 | 101 | 47 | 59 | 56 | 9 | 35 | 8 | 23 | 30 | 30 | 27 | 11 | 17 | 18 | 21 | 59 | 89 |
Wind waves Height (m) Direction Period (s) | SSW 5 | SW 5 | SW 6 | SSW 5 | SSW 6 | SW 6 | SSW 6 | S 9 | SSW 6 | SSW 6 | — | NE 4 | NE 5 | ENE 5 | ENE 5 | — | — | SW 10 | SSW 4 | SSW 5 |
| kJ | 37 | 49 | 83 | 52 | 93 | 100 | 29 | 168 | 59 | 117 | — | 26 | 60 | 41 | 37 | — | — | 48 | 14 | 7 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 240 | 18 | 9 | 598 | 18 | 0 | 0 | 23 | 2 | 18 | 0 | 51 | 56 | 0 | 0 | 9 | 0 | 0 | 9 | 0 |
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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