Surf Forecasts:
Onjuku surf forecast from 28 Aug 2026:
- Best quality surf: Saturday 29 Aug, 12AM (local time) - 2ft (0.6m), 12s period, E swell with cross-offshore winds.
- Most powerful swell: Tuesday 1 Sep, 6PM (local time) - 3.5ft (1.0m), 12s period, ESE swell with 288 kJ wave energy.
- Next surfable swell (1★+): Saturday 29 Aug, 12AM (local time) - 2ft (0.6m), 12s 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 Saturday (Aug 29) at 12AM. The primary swell is predicted to be 0.6m and 12s period with a secondary swell of 0.7m and 6s. 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 1.0m 12s and forecast to arrive on Tuesday (Sep 01) at 6PM. Winds are predicted to be onshore 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 6PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12AM (Sat 29th Aug) | 2ft (0.6m) 12s |
| Best Surf | 12AM (Sat 29th Aug) | 2ft (0.6m) 12s |
| Most Powerful | 6PM (Tue 1st Sep) | 3.5ft (1.0m) 12s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s look at what’s shaping up for the coming days.
Alright, we’re looking at a pretty quiet start for Onjuku. The first half of the window is a bit of a struggle with mostly small, mixed-up conditions. We’ve got a few days of weak, short-period windswell with a lot of cross-shore wind, so nothing really worth paddling out for. That run from Friday the 30th through to Monday the 2nd of September is mostly clean, but the waves are tiny – around 1ft to 2ft – and the energy is low (86 to 144). There’s a hint of a glassy moment on Monday morning the 31st of August, but it’s just too small to get excited about.
We do see a bit of a pulse around Tuesday the 3rd of September, with some waist-high sets, but the wind is howling from the SSW, making it choppy and messy. Not our day.
Now, hold on, because the real story is way out at the end of the forecast. On Friday the 11th of September, a monster groundswell is forecast to light up the joint. The morning sees a solid 10ft swell from the SE with a very long period of 19 seconds. The energy is absolutely pumping (7050). The wind is a light offshore from the ENE, so the break will be clean. This is a big, serious wave with a very long period, which means it will be powerful and probably best for the point break setup at Onjuku. The period is so long it might make the waves a bit too straight in the beachy sections, but for the experienced crew, this is the standout. This is not for beginners; it’s well over 8ft.
The water is a touch warmer than normal for this time of year, coming in at 82°F.
So, the pick of the whole 16-day window is undeniably the morning of Friday the 11th of September. It’s a long way off, so the forecast could shift, but if it holds, that’s the one to circle. The afternoon of the 11th gets even bigger (13ft) and the afternoon of the 12th is massive (16ft), but those are so big they might be too much for the break, and the wind turns onshore.
Rusty.
Short Range ForecastModerate rain (total 11mm), heaviest on Fri afternoon. Warm (max 31°C on Fri afternoon, min 23°C on Sat afternoon). Wind will be generally light. | Days 5-7 Weather SummarySome drizzle, heaviest during Wed night. Warm (max 29°C on Thu morning, min 26°C on Mon night). Wind will be generally light. | |||||||||||||||||||
Fri 28 | Saturday 29 | Sunday 30 | Monday 31 | Tuesday 1 | Wednesday 2 | Thursday 3 | ||||||||||||||
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) | SW 7 | E 12 | E 12 | E 11 | E 11 | E 11 | E 11 | E 11 | E 11 | E 11 | ESE 12 | ESE 11 | ESE 11 | ESE 11 | ESE 10 | S 12 | S 10 | SSW 10 | E 11 | SSW 10 |
Wave Graph  | ||||||||||||||||||||
 kJ | 192 | 99 | 96 | 60 | 58 | 59 | 61 | 57 | 37 | 70 | 169 | 221 | 229 | 254 | 115 | 171 | 164 | 144 | 114 | 86 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-off | cross | cross-off | cross-off | cross-off | cross-off | cross-off | glassy | cross-on | cross-on | on | on | cross-on | on | on | on | cross-on | cross-on | cross-on |
High Tide | 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 | 8:31AM1.12m | 7:17PM1.40m | |||||||
Low Tide | 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 | 1:12PM0.84m | 2:52AM0.34m | |||||||
 |  | |  |  | |  |  |  |  |  | | | | | | | | | | |
 | — | — | 5:07 | — | — | 5:07 | — | — | 5:09 | — | — | 5:09 | — | — | 5:11 | — | — | 5:11 | — | — |
 | 6:12 | — | — | 6:09 | — | — | 6:08 | — | — | 6:07 | — | — | 6:06 | — | — | 6:05 | — | — | 6:04 | — |
mm | 1 | 3 | 1 | — | 3 | 2 | 1 | — | — | — | — | — | — | — | — | — | 1 | — | — | — |
Temp °C | 31 | 27 | 25 | 24 | 24 | 25 | 25 | 24 | 27 | 28 | 26 | 28 | 28 | 26 | 28 | 28 | 27 | 29 | 28 | 27 |
Feels °C | 34 | 32 | 26 | 23 | 24 | 28 | 29 | 28 | 30 | 30 | 29 | 31 | 30 | 30 | 31 | 31 | 31 | 30 | 28 | 27 |
Swell 1 Height (m) Direction Period (s) | SSW 6 | SSW 6 | E 12 | E 11 | E 11 | E 5 | E 5 | E 5 | E 11 | ESE 13 | ESE 12 | ESE 11 | ESE 11 | ESE 11 | ESE 10 | S 12 | S 10 | SE 6 | SE 6 | SE 6 |
| kJ | 77 | 37 | 96 | 60 | 58 | 36 | 19 | 20 | 37 | 70 | 169 | 221 | 229 | 254 | 115 | 171 | 164 | 56 | 60 | 59 |
Swell 2 Height (m) Direction Period (s) | E 12 | E 12 | S 8 | SE 11 | SE 10 | E 11 | E 11 | E 11 | ESE 5 | E 11 | E 6 | S 11 | S 10 | S 10 | S 10 | ESE 10 | ESE 6 | SSW 10 | SSW 10 | SSW 10 |
| kJ | 103 | 99 | 18 | 30 | 27 | 59 | 61 | 57 | 8 | 57 | 18 | 58 | 73 | 75 | 98 | 114 | 35 | 144 | 108 | 86 |
Swell 3 Height (m) Direction Period (s) | S 8 | S 8 | SW 6 | S 8 | SSW 8 | SE 10 | SE 10 | SE 10 | SE 9 | NE 6 | S 10 | E 6 | NE 7 | NE 7 | ESE 6 | ESE 7 | ESE 10 | E 10 | E 11 | E 10 |
| kJ | 45 | 20 | 10 | 19 | 11 | 26 | 26 | 25 | 22 | 10 | 52 | 11 | 7 | 7 | 12 | 15 | 75 | 65 | 114 | 71 |
Wind waves Height (m) Direction Period (s) | SW 7 | NE 3 | NE 4 | ENE 5 | E 5 | — | — | SSW 3 | SW 4 | SSW 4 | SW 4 | — | E 6 | — | — | — | — | — | — | — |
| kJ | 192 | 1 | 15 | 55 | 71 | — | — | 1 | 19 | 7 | 5 | — | 11 | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 2 | 0 | 56 | 132 | 557 | 16 | 0 | 0 | 0 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 143 | 583 | 88 |
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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