
Surf Forecasts:
Onjuku surf forecast from 5 Aug 2026:
- Best quality surf: Wednesday 5 Aug, 12PM (local time) - 11ft (3.5m), 14s period, SE swell with cross-offshore winds.
- Most powerful swell: Wednesday 5 Aug, 12PM (local time) - 11ft (3.5m), 14s period, SE swell with 5,001 kJ wave energy.
- Next surfable swell (1★+): Wednesday 5 Aug, 12PM (local time) - 11ft (3.5m), 14s period with SE 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 Wednesday (Aug 05) at 12PM. The primary swell is predicted to be 3.5m and 14s period with a secondary swell of 0.1m and 18s. 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 3.5m 14s and forecast to arrive on Wednesday (Aug 05) 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 1.8m 9s period and expected on Wednesday (Aug 12) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12PM (Wed 5th Aug) | 11ft (3.5m) 14s |
| Best Surf | 12PM (Wed 5th Aug) | 11ft (3.5m) 14s |
| Most Powerful | 12PM (Wed 5th Aug) | 11ft (3.5m) 14s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, let's talk about Onjuku. The surf is going to be a bit of a rollercoaster – some serious, heavy juice coming through, but a lot of it is just going to be too much for this place. The water is at 81°, which is normal for the season.
The first big one is Wednesday morning, August 5th. We've got a solid 12ft of SE groundswell, and the energy is huge – reading 5405 on the scale, which is strong to very strong. The wind is a cross-off at 19 mph, so it'll be clean, but this is a beast. It's well over the 8ft mark, so it's strictly for the experts. The afternoon stays similar, still too big for the average punter.
Thursday the 6th eases off to 7ft with a better SSE direction, and the wind goes light and cross-off. This is the window for the experienced surfer. The morning looks excellent with a 12-second period. The afternoon gets a bit more chopped with a cross-shore breeze, so get on it early.
Friday the 7th through Sunday the 9th sees the swell back off to the 5ft – 7ft range, but the wind turns onshore and it gets messy. Energy is moderate at best. It's not going to be fun, just a bit of a battle. Monday the 10th is clean with a fresh offshore wind, but the swell is only 6ft and the period has dropped. It's surfable, but nothing to write home about.
Now, Tuesday the 11th is the other big one. We've got another 12ft blast, this time from the ENE, and the energy is through the roof at 5481. The morning wind is cross-off, so it's clean, but again, it's a monster. Way too big for anyone but the pros. The afternoon wind goes fully offshore but it's blowing 25 mph, making it a mission to even paddle out. The size drops to 8ft, but that wind is a battle.
The rest of that week into the 16th is a letdown. The swell drops, and the energy is weak. The wind is mostly cross-offshore, but the waves are small and weak.
The second week has a pulse though. Around the 17th and 18th, we see the swell picking up again to the 6ft – 6ft range. The period is a bit short, around 8-9 seconds, so it won't have the same grunt, but the wind is light and clean. It's promising, but it's a long way out, so we'll see.
The standout days are the big ones on the 5th and the 11th. They're for experts only. For the rest of us, the morning of the 6th is the best bet for a clean, powerful session without the sheer terror. This break is exposed, and a lot of the time the swell is just too big, turning it into a washing machine. With all that size and the onshore winds later in the week, it might be more interesting for the kite surfers than us paddle surfers.
Rusty.
Short Range ForecastSome drizzle, heaviest during Thu morning. Warm (max 28°C on Thu morning, min 24°C on Wed morning). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 2mm), mostly falling on Sat morning. Warm (max 27°C on Sat morning, min 23°C on Sun night). Winds increasing (light winds from the ENE on Sat night, fresh winds from the NNE by Mon morning). | ||||||||||||||||||||
Wednesday 5 | Thursday 6 | Friday 7 | Saturday 8 | Sunday 9 | Monday 10 | Tuesday 11 | |||||||||||||||
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) | SE 15 | SE 14 | SE 13 | SSE 12 | SSE 13 | S 14 | S 14 | S 13 | S 13 | S 13 | S 13 | ESE 13 | ESE 14 | ESE 13 | ESE 13 | E 12 | E 12 | ENE 11 | ENE 12 | ENE 11 | ENE 10 |
Wave Graph | |||||||||||||||||||||
5330 | 4542 | 2682 | 1523 | 1584 | 1905 | 1918 | 1271 | 972 | 737 | 737 | 812 | 1122 | 975 | 874 | 1022 | 911 | 1540 | 3210 | 1422 | 1710 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | cross-off | cross-off | cross | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-off | cross-off | cross-off | cross-off | off | off | off | cross-off | off | off |
High Tide | 8:17PM1.37m | 9:58AM1.02m | 8:49PM1.35m | 12:56PM1.00m | 9:31PM1.33m | 10:43PM1.31m | 4:10PM1.23m | 00:23AM1.32m | 4:33PM1.30m | 1:48AM1.37m | 4:57PM1.35m | 2:54AM1.44m | |||||||||
Low Tide | 1:55PM0.69m | 3:27AM0.45m | 2:20PM0.85m | 4:43AM0.41m | 2:29PM1.00m | 6:13AM0.33m | 7:36AM0.23m | 7:43PM1.16m | 8:40AM0.12m | 8:57PM1.09m | 9:31AM0.04m | 9:44PM0.99m | |||||||||
4:48 | — | — | 4:50 | — | — | 4:50 | — | — | 4:52 | — | — | 4:52 | — | — | 4:52 | — | — | 4:54 | — | — | |
— | 6:38 | — | — | 6:37 | — | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — | — | 6:32 | — | — | 6:31 | — | |
mm | — | — | — | 1 | — | — | — | — | — | 1 | — | — | — | — | — | — | — | 1 | — | — | 5 |
Temp °C | 25 | 26 | 25 | 28 | 28 | 26 | 27 | 27 | 25 | 27 | 27 | 25 | 27 | 26 | 24 | 24 | 25 | 24 | 27 | 27 | 24 |
Feels °C | 24 | 27 | 28 | 31 | 31 | 30 | 29 | 29 | 28 | 30 | 29 | 28 | 27 | 26 | 23 | 21 | 22 | 22 | 25 | 23 | 21 |
Swell 1 Height (m) Direction Period (s) | SE 15 | SE 14 | SE 13 | SSE 12 | SSE 13 | S 14 | S 14 | S 13 | S 13 | S 13 | S 13 | ESE 13 | ESE 14 | ESE 13 | ESE 13 | E 12 | E 12 | S 12 | E 12 | SSW 14 | E 10 |
5330 | 4542 | 2682 | 1523 | 1584 | 1905 | 1918 | 1271 | 972 | 737 | 737 | 812 | 1122 | 975 | 874 | 1022 | 911 | 151 | 1946 | 289 | 980 | |
Swell 2 Height (m) Direction Period (s) | ENE 12 | E 18 | E 16 | ESE 10 | ESE 10 | ESE 10 | ESE 10 | ESE 10 | ESE 10 | ESE 9 | ESE 12 | S 13 | S 13 | S 12 | SSW 16 | S 11 | SSW 15 | SW 15 | SSW 14 | SE 10 | SSW 13 |
50 | 24 | 21 | 377 | 305 | 346 | 290 | 284 | 284 | 272 | 508 | 539 | 459 | 300 | 754 | 149 | 376 | 183 | 325 | 4 | 246 | |
Swell 3 Height (m) Direction Period (s) | E 18 | — | ENE 16 | E 16 | E 16 | E 15 | E 15 | E 15 | E 14 | E 14 | E 14 | ENE 14 | SW 15 | SW 15 | SE 10 | SW 15 | S 11 | SE 11 | — | — | — |
25 | — | 26 | 20 | 20 | 41 | 39 | 39 | 37 | 36 | 15 | 62 | 112 | 284 | 4 | 178 | 112 | 5 | — | — | — | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | NNE 4 | NE 5 | ENE 11 | ENE 12 | ENE 11 | ENE 10 |
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 40 | 61 | 1540 | 3210 | 1422 | 1710 | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 78 | 56 | 0 | 0 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 0 | 51 | 117 | 2130 | 2130 | 2120 | 1081 | 206 | 557 | 200 |
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.











