
Surf Forecasts:
Onjuku surf forecast from 6 Aug 2026:
- Best quality surf: Sunday 9 Aug, 3AM (local time) - 5.5ft (1.7m), 14s period, ESE swell with glassy winds.
- Most powerful swell: Tuesday 11 Aug, 3AM (local time) - 10ft (3.0m), 12s period, ENE swell with 2,155 kJ wave energy.
- Next surfable swell (1★+): Sunday 9 Aug, 3AM (local time) - 5.5ft (1.7m), 14s period with ESE 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 Sunday (Aug 09) at 3AM. The primary swell is predicted to be 1.7m and 14s period with a secondary swell of 0.9m and 11s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 3.0m 12s and forecast to arrive on Tuesday (Aug 11) at 3AM. Winds are predicted to be offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.6m 4s period and expected on Friday (Aug 14) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Sun 9th Aug) | 5.5ft (1.7m) 14s |
| Best Surf | 3AM (Sun 9th Aug) | 5.5ft (1.7m) 14s |
| Most Powerful | 3AM (Tue 11th Aug) | 10ft (3.0m) 12s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s take a look at what’s shaping up for Onjuku over the next couple of weeks. It’s a bit of a mixed bag, with a real standout session on the horizon, but we’ve got to wade through some ordinary conditions first.
The forecast starts off pretty average for Friday the 7th. We’ve got a south swell pushing through at around 6 feet, but the wind is straight on it from the SSE. It’s going to be a messy, marginal affair. The energy is high, but with the onshore breeze, it’s not going to be pretty. That combo rolls into Saturday with the swell dropping a bit, and the wind swinging SE, keeping things cross-onshore and choppy. Nothing to get excited about yet.
Now, Sunday the 9th is where things start to look up. The wind swings around to a cross-offshore from the ENE, which cleans the face right up. We’re looking at a solid 6 feet groundswell from the ESE with a long period of 13 seconds. The energy is strong. For an intermediate spot, this is a good call – clean lines, decent power. The morning session is the pick, with a light breeze keeping it glassy.
Monday sees the swell holding around 6 feet from the east, but the wind really picks up from the NNE at 19 mph. It’s cross-offshore, so it stays clean, but it’s a fresh breeze and the energy is still solid. It’s surfable, but the wind will make it a bit of a battle.
Then we get to Tuesday the 11th. The morning looks punchy with an 8 feet swell from the ENE. That’s getting up there in size, definitely for experienced surfers only. The wind is straight offshore from the NNE at 22 mph, so the faces will be pristine, but that’s a strong breeze to paddle into. The energy is massive, meaning there’s a lot of water moving around. It’s powerful, and if you’re not on your game, it’ll put you in your place. The afternoon sees the size drop right off, and the wind gets messy, so the morning is your only window.
After that, we hit a bit of a lull. Wednesday and Thursday see the swell drop and the wind gets flukey, with some onshore or cross-off conditions that just don’t come together. There’s a gap here with no real recommendations until the weekend.
Now, for the real standout: Sunday the 16th. Mark this one. The morning is looking excellent. We’ve got a solid 10 feet swell from the east with an 11-second period. That’s big, expert-only territory. The wind is a gentle cross-offshore from the ENE, and the energy reading is huge. The report calls it excellent for experienced surfers, and I agree. The waves will have plenty of power and the offshore wind will keep them clean and lined up. This is the best on offer for the entire period. The afternoon drops back to 8 feet, still solid, but the morning is the main event.
The following week gets a bit hit-or-miss. Monday the 17th still has some size at 8 feet, but the wind is a strong cross-offshore, making it a handful. The rest of the week sees the swell fade and the wind patterns shift around, with only Thursday the 20th offering a glimmer of hope with a 5 feet swell and cleaner cross-offshore conditions.
The water temperature is about average for this time of year, so no major surprises there.
So, to sum it up: the first few days are average, Sunday the 9th is a nice little warm-up, but the real prize is Sunday morning the 16th for the experienced crew. Get on it.
Rusty.
Short Range ForecastLight rain (total 4mm), mostly falling on Thu night. Warm (max 28°C on Fri morning, min 24°C on Sat night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 7mm), mostly falling on Wed afternoon. Warm (max 26°C on Mon morning, min 23°C on Sun night). Winds increasing (light winds from the NE on Sun night, strong winds from the NNE by Tue afternoon). | ||||||||||||||||||
Friday 7 | Saturday 8 | Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | ||||||||||||||
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 13 | S 12 | S 12 | S 11 | S 11 | ESE 13 | ESE 14 | ESE 13 | ESE 13 | ESE 12 | E 12 | E 11 | ENE 11 | ENE 11 | E 10 | ENE 10 | ENE 10 | E 10 | E 11 |
Wave Graph | |||||||||||||||||||
1684 | 948 | 702 | 457 | 344 | 624 | 1053 | 998 | 917 | 876 | 997 | 872 | 1134 | 1463 | 510 | 370 | 168 | 235 | 610 | |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | on | on | cross-on | cross-on | on | cross-off | cross-off | off | cross-off | cross-off | off | off | cross-off | off | off | off | on |
High Tide | 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 | 5:21PM1.37m | |||||||||
Low Tide | 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 | 10:15AM0.00m | 10:23PM0.88m | ||||||||
— | 4:50 | — | — | 4:52 | — | — | 4:52 | — | — | 4:52 | — | — | 4:54 | — | — | 4:54 | — | — | |
6:37 | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | |
mm | 2 | 2 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 7 | 41 |
Temp °C | 27 | 28 | 28 | 25 | 27 | 27 | 25 | 27 | 26 | 24 | 26 | 26 | 23 | 26 | 26 | 24 | 26 | 23 | 26 |
Feels °C | 31 | 31 | 30 | 28 | 30 | 28 | 28 | 28 | 26 | 26 | 23 | 24 | 20 | 22 | 22 | 21 | 24 | 22 | 28 |
Swell 1 Height (m) Direction Period (s) | S 13 | S 12 | S 12 | S 11 | ESE 10 | ESE 13 | ESE 14 | ESE 13 | ESE 13 | ESE 12 | E 12 | E 11 | E 11 | E 11 | E 10 | ENE 10 | ENE 10 | E 10 | E 11 |
1684 | 948 | 702 | 457 | 241 | 624 | 1053 | 998 | 917 | 876 | 997 | 872 | 850 | 878 | 510 | 370 | 168 | 235 | 610 | |
Swell 2 Height (m) Direction Period (s) | ESE 10 | ESE 9 | ESE 9 | ESE 9 | S 11 | S 11 | S 11 | S 10 | S 11 | S 10 | S 12 | S 11 | E 14 | S 12 | S 11 | S 11 | ESE 10 | SSW 11 | S 11 |
346 | 327 | 288 | 288 | 344 | 284 | 235 | 138 | 143 | 138 | 130 | 114 | 186 | 98 | 89 | 88 | 123 | 93 | 83 | |
Swell 3 Height (m) Direction Period (s) | E 15 | E 15 | E 15 | E 14 | E 14 | E 10 | — | — | SE 16 | SW 12 | SW 15 | SW 14 | S 10 | SW 12 | SW 12 | SE 13 | SSW 11 | NE 9 | NE 9 |
41 | 39 | 39 | 37 | 36 | 46 | — | — | 10 | 116 | 9 | 8 | 74 | 68 | 49 | 6 | 97 | 54 | 77 | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | ENE 11 | ENE 11 | — | — | — | — | — |
— | — | — | — | — | — | — | — | — | — | — | — | 1134 | 1463 | — | — | — | — | — | |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 0 | 56 | 0 | 51 | 51 | 82 | 205 | 143 | 78 | 69 | 68 | 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.











