Surf Forecasts:
Onjuku surf forecast from 26 Aug 2026:
- Best quality surf: Thursday 27 Aug, 6PM (local time) - 2.5ft (0.7m), 13s period, E swell with offshore winds.
- Most powerful swell: Wednesday 2 Sep, 12PM (local time) - 4.5ft (1.3m), 16s period, SSW swell with 839 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 0.8m and 10s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 1.3m 16s and forecast to arrive on Wednesday (Sep 02) 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 1.0m 5s period and expected on Sunday (Aug 30) at 9PM.
| 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 (Wed 2nd Sep) | 4.5ft (1.3m) 16s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, grab a coffee, let's have a look at what's going on for Onjuku.
Honestly mate, the next week and a half is a bit of a write-off. We’ve got a real slow patch here from now through the end of August and into the first few days of September. There are reports of swell, but the wind is all over the shop, mostly cross-onshore, and that's just messing up the surface on what would otherwise be a fun little wave. The energy is there, but the quality isn't. Most of that time, we're looking at poor surf conditions with the odd marginal session if you’re desperate for a paddle. The water is sitting at about 82°F right now, which feels a touch warmer than normal for this time of year, so at least the wait won't be chilly.
Things start to get a bit more interesting towards the back half of the first week of September. There’s a pulse of very long period groundswell from the SSW arriving around Wednesday the 2nd. We’re talking 4ft to 4ft with a period of 15 seconds, and the combined energy is going to be strong at around 1200. It’s a fair bit of juice, but with winds directly onshore and a beach break setup, it’s going to be a messy, blown-out mess. This kind of long period groundswell needs a point or reef to shine. Honestly, with that wind and power, the setup looks more interesting for kite surfing than a clean paddle session.
The real standout, and the only one I’d circle on the calendar, is Wednesday the 9th of September. After all that junk, we get clean, offshore winds from the north. The swell drops back to a very manageable 5ft from the south with a decent 11-second period. The combined energy is moderate (542), but it's that light offshore wind that makes the difference. Expect some clean, lined-up sets, and given Onjuku is inconsistent, it's a real treat when the stars align. If you can only pick one day in the next two weeks, that's your morning session right there. Keep in mind it’s a high-quality window, not a huge swell, but clean and workable. Crowds are sometimes a thing here, so get in early.
Late on Saturday the 5th, there is a brief window of glassy conditions with a 5ft ENE windswell, but it’s not the strongest and the quality is only rated as good, not great. It's an option for the die-hards but Wednesday the 9th is where the real fun is.
Rusty
Short Range ForecastModerate rain (total 19mm), heaviest on Thu morning. Warm (max 30°C on Wed morning, min 23°C on Thu afternoon). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 4mm), mostly falling on Sun afternoon. Warm (max 26°C on Sat morning, min 24°C on Sun night). Wind will be generally light. | ||||||||||||||||||||
Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | Monday 31 | Tuesday 1 | |||||||||||||||
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) | S 10 | SSE 9 | SSE 9 | SSE 10 | E 13 | E 13 | E 12 | E 12 | E 12 | E 12 | E 11 | E 11 | E 11 | E 11 | E 11 | NE 7 | NE 7 | ENE 7 | E 8 | ENE 8 | SSW 14 |
Wave Graph  | |||||||||||||||||||||
 kJ | 257 | 146 | 121 | 120 | 173 | 163 | 148 | 139 | 99 | 96 | 63 | 61 | 58 | 59 | 57 | 79 | 91 | 94 | 127 | 100 | 269 |
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-off | cross-on | cross-on | cross-on | cross-off | cross-off | cross-off | cross-off | cross-on | cross | cross-off | cross-off | cross-off | cross-off | cross | cross-on | on |
High Tide | 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 | 6:41AM1.32m | 6:31PM1.44m | ||||||||
Low Tide | 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 | 12:27PM0.56m | 1:09AM0.32m | |||||||
 | |  |  |  |  | | |  |  | | |  | | | | | | | |  | |
 | 5:05 | — | — | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — | 5:07 | — | — | 5:09 | — | — | 5:09 | — | — |
 | — | 6:14 | — | — | 6:13 | — | — | 6:12 | — | — | 6:09 | — | — | 6:08 | — | — | 6:07 | — | — | 6:06 | — |
mm | — | — | 1 | 7 | 4 | 5 | 1 | 1 | — | — | — | — | — | 1 | 3 | — | — | — | — | — | 3 |
Temp °C | 30 | 29 | 27 | 28 | 24 | 25 | 28 | 27 | 26 | 26 | 26 | 25 | 26 | 26 | 25 | 24 | 26 | 24 | 28 | 28 | 27 |
Feels °C | 32 | 30 | 28 | 29 | 25 | 27 | 30 | 29 | 28 | 25 | 25 | 26 | 29 | 30 | 28 | 26 | 28 | 26 | 31 | 31 | 30 |
Swell 1 Height (m) Direction Period (s) | S 10 | SSE 9 | SSE 9 | SSE 10 | SSW 6 | S 9 | E 12 | SSW 8 | E 12 | E 12 | E 11 | E 11 | E 11 | E 11 | E 11 | E 11 | E 10 | ENE 7 | E 8 | ENE 8 | SSE 10 |
| kJ | 257 | 146 | 121 | 120 | 38 | 134 | 148 | 90 | 99 | 96 | 63 | 61 | 58 | 59 | 57 | 55 | 49 | 94 | 127 | 99 | 157 |
Swell 2 Height (m) Direction Period (s) | S 12 | ESE 12 | E 12 | E 11 | E 13 | E 13 | S 9 | E 12 | SSW 5 | S 8 | SSW 8 | ENE 5 | SE 10 | SE 10 | SSW 7 | SE 9 | SE 9 | S 10 | S 10 | S 10 | SSW 14 |
| kJ | 101 | 113 | 70 | 59 | 173 | 163 | 56 | 139 | 10 | 29 | 19 | 8 | 26 | 26 | 9 | 23 | 23 | 71 | 66 | 100 | 269 |
Swell 3 Height (m) Direction Period (s) | ESE 12 | S 12 | SSW 11 | E 14 | SSE 10 | SE 10 | SSE 9 | SE 9 | SSW 8 | SE 11 | SE 11 | SSW 8 | SSW 8 | SSW 7 | SE 10 | S 13 | SSE 12 | SE 10 | ESE 11 | ESE 10 | ESE 10 |
| kJ | 117 | 101 | 47 | 64 | 80 | 26 | 34 | 22 | 21 | 30 | 30 | 19 | 19 | 10 | 26 | 28 | 46 | 28 | 46 | 68 | 82 |
Wind waves Height (m) Direction Period (s) | SW 5 | SSW 5 | SSW 5 | SSW 6 | NE 3 | SSW 6 | — | SW 6 | SW 6 | NE 4 | NE 5 | — | — | NNE 3 | NE 5 | NE 7 | NE 7 | — | — | — | S 6 |
| kJ | 58 | 44 | 44 | 55 | 5 | 22 | — | 68 | 38 | 24 | 36 | — | — | 7 | 37 | 79 | 91 | — | — | — | 77 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 9 | 88 | 88 | 18 | 40 | 2 | 18 | 17 | 0 | 56 | 240 | 0 | 9 | 12 | 0 | 22 | 16 | 0 | 51 | 9 | 9 |
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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