Surf Forecasts:
Onjuku surf forecast from 9 Aug 2026:
- Best quality surf: Tuesday 11 Aug, 9AM (local time) - 7ft (2.2m), 12s period, E swell with offshore winds.
- Most powerful swell: Monday 10 Aug, 12PM (local time) - 8ft (2.5m), 12s period, ENE swell with 1,774 kJ wave energy.
- Next surfable swell (1★+): Tuesday 11 Aug, 9AM (local time) - 7ft (2.2m), 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 Tuesday (Aug 11) at 9AM. The primary swell is predicted to be 2.2m and 12s period with a secondary swell of 0.5m and 11s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 2.5m 12s and forecast to arrive on Monday (Aug 10) at 12PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 2.4m 8s period and expected on Tuesday (Aug 11) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Tue 11th Aug) | 7ft (2.2m) 12s |
| Best Surf | 9AM (Tue 11th Aug) | 7ft (2.2m) 12s |
| Most Powerful | 12PM (Mon 10th Aug) | 8ft (2.5m) 12s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s have a look at what’s coming up for Onjuku.
The surf window starts on Monday the 10th, but honestly, it’s a bit of a rough start. The waves are there, around 7ft from the east, but a fresh cross-off wind makes it messy. The water is a warm 81°, which is pretty average for this time of year – no surprises there. The combined energy is strong, sitting at 1460 (moderate wave energy), but the quality just isn’t there yet. Monday afternoon is much the same story.
Things start to look up on Tuesday the 11th. The morning is a real standout. The swell is still a solid 7ft from the east, with a 12-second period, and the wind turns offshore from the north at 16 mph. That’s going to clean things right up. The combined energy is strong at 1419 (moderate wave energy). This is for experienced surfers only, as it’s over 8ft. If you’re up for it, this is the best session of the whole run. Tuesday afternoon drops off a bit as the wind goes cross and the swell drops.
Wednesday the 12th and Thursday the 13th are a bit average – the swell drops to around 4ft to 5ft with a short period, and the wind is mostly cross-off. The energy drops right off into the hundreds (346 to 529). Surfable, but nothing to write home about.
Friday the 14th is another good call. The morning has offshore winds from the north-northeast at 12 mph and a clean 6ft east swell with a 10-second period. The energy is moderate at 766. That’s a solid session for intermediates.
Then we hit a big gap. From Saturday the 15th right through to Tuesday the 25th, it’s pretty bleak. The swell stays small, the winds get messy, and the energy is low, often under 300. There are a couple of pulses, like on Tuesday the 25th afternoon with a 5ft swell from the south-southeast and a 12-second period, but the fresh cross-onshore wind kills it. The combined energy is 652, but with that wind, it’s just not worth it for paddling. Honestly, that setup looks more interesting for kite surfing than paddle surfing.
The only real standout in this whole forecast is Tuesday the 11th of August morning. Strong east swell, offshore wind, and clean conditions. Get on it if you can. After that, it’s a long wait.
Rusty.
Short Range ForecastHeavy rain (total 36mm), heaviest during Tue afternoon. Warm (max 27°C on Mon morning, min 22°C on Mon night). Winds decreasing (fresh winds from the NE on Mon afternoon, light winds from the NE by Wed afternoon). | Days 4-6 Weather SummaryHeavy rain (total 42mm), heaviest during Sat morning. Warm (max 28°C on Thu afternoon, min 22°C on Sat night). Winds increasing (light winds from the ENE on Fri night, fresh winds from the NNE by Sat night). | ||||||||||||||||||||
Monday 10 | Tuesday 11 | Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | |||||||||||||||
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) | E 12 | E 11 | ENE 10 | E 12 | E 12 | E 11 | E 10 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 10 | ENE 10 | ENE 10 | ENE 10 | E 10 | E 10 | E 9 | E 9 |
Wave Graph  | |||||||||||||||||||||
 kJ | 1344 | 1213 | 920 | 1319 | 827 | 790 | 266 | 235 | 288 | 390 | 474 | 592 | 703 | 592 | 838 | 874 | 821 | 539 | 524 | 539 | 481 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | off | off | cross | on | cross-on | cross-off | off | cross-off | cross-off | off | off | cross-off | cross-off | cross-off | cross-off | off | off | cross-off | cross-off |
High Tide | 4:33PM1.30m | 1:48AM1.37m | 4:57PM1.35m | 2:54AM1.44m | 5:21PM1.37m | 3:50AM1.49m | 5:43PM1.38m | 4:40AM1.50m | 6:04PM1.38m | 5:27AM1.47m | 6:24PM1.39m | 6:12AM1.40m | 6:43PM1.39m | ||||||||
Low Tide | 8:57PM1.09m | 9:31AM0.04m | 9:44PM0.99m | 10:15AM0.00m | 10:23PM0.88m | 10:54AM0.03m | 11:01PM0.75m | 11:29AM0.11m | 11:38PM0.63m | 12:00PM0.24m | 00:15AM0.53m | 12:27PM0.38m | 00:54AM0.46m | ||||||||
 | |  |  |  |  |  |  | | |  | | | |  | | |  | | | | |
 | 4:52 | — | — | 4:54 | — | — | 4:54 | — | — | 4:56 | — | — | 4:56 | — | — | 4:56 | — | — | 4:58 | — | — |
 | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:29 | — | — | 6:28 | — | — | 6:27 | — |
mm | — | — | — | — | 13 | 17 | 5 | 1 | — | 2 | — | — | — | 2 | 4 | 17 | 4 | 13 | — | — | 3 |
Temp °C | 27 | 26 | 24 | 27 | 23 | 24 | 25 | 26 | 25 | 27 | 28 | 25 | 27 | 27 | 26 | 25 | 25 | 24 | 25 | 24 | 24 |
Feels °C | 26 | 24 | 22 | 26 | 23 | 24 | 25 | 28 | 27 | 29 | 30 | 27 | 29 | 30 | 29 | 25 | 25 | 21 | 22 | 20 | 27 |
Swell 1 Height (m) Direction Period (s) | E 12 | SSW 11 | S 10 | E 12 | E 12 | E 11 | E 10 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 10 | ENE 10 | SSE 9 | SSW 11 | E 10 | E 10 | E 9 | E 9 |
| kJ | 1344 | 97 | 55 | 1319 | 827 | 790 | 266 | 235 | 288 | 390 | 474 | 592 | 703 | 592 | 838 | 47 | 40 | 539 | 524 | 539 | 481 |
Swell 2 Height (m) Direction Period (s) | S 11 | SSW 11 | SE 14 | S 11 | NE 9 | S 10 | S 10 | S 10 | S 10 | S 10 | S 10 | SSW 9 | SSW 9 | SSW 9 | SSE 9 | SSW 9 | SSE 13 | S 12 | S 10 | SSE 11 | SSE 11 |
| kJ | 93 | 91 | 8 | 57 | 294 | 74 | 75 | 75 | 51 | 50 | 49 | 29 | 28 | 28 | 29 | 8 | 16 | 102 | 77 | 81 | 78 |
Swell 3 Height (m) Direction Period (s) | SW 12 | SW 11 | — | SW 11 | S 11 | SW 10 | SSE 4 | SSE 12 | SE 12 | — | SE 12 | SSE 11 | SE 12 | SE 11 | SSW 9 | S 11 | SSE 10 | SSE 12 | SSE 12 | S 10 | S 9 |
| kJ | 23 | 103 | — | 43 | 58 | 69 | 5 | 13 | 6 | — | 6 | 13 | 35 | 29 | 15 | 10 | 10 | 93 | 93 | 47 | 43 |
Wind waves Height (m) Direction Period (s) | NNE 5 | E 11 | ENE 10 | NE 9 | NW 4 | SSW 3 | — | NE 8 | NE 8 | — | — | — | NNE 4 | NE 4 | NNE 5 | ENE 10 | ENE 10 | — | — | — | — |
| kJ | 69 | 1213 | 920 | 727 | 12 | 8 | — | 82 | 57 | — | — | — | 28 | 32 | 107 | 874 | 821 | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 56 | 51 | 51 | 0 | 2 | 553 | 9 | 0 | 0 | 0 | 16 | 0 | 0 | 0 | 0 | 206 | 557 | 206 | 200 | 102 | 45 |
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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