
Surf Forecasts:
Onjuku surf forecast from 5 Aug 2026:
- Best quality surf: Wednesday 5 Aug, 3PM (local time) - 11ft (3.5m), 14s period, SE swell with cross-offshore winds.
- Most powerful swell: Wednesday 5 Aug, 3PM (local time) - 11ft (3.5m), 14s period, SE swell with 4,542 kJ wave energy.
- Next surfable swell (1★+): Wednesday 5 Aug, 3PM (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 3PM. The primary swell is predicted to be 3.5m and 14s period with a secondary swell of 0.2m 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 3PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.6m 6s period and expected on Monday (Aug 10) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Wed 5th Aug) | 11ft (3.5m) 14s |
| Best Surf | 3PM (Wed 5th Aug) | 11ft (3.5m) 14s |
| Most Powerful | 3PM (Wed 5th Aug) | 11ft (3.5m) 14s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, surfers, Rusty here. Let's cut through the noise and look at what's actually on the menu for our stretch of coast. This is a long-range look, so keep that in mind – the early calls are solid, but the further out we go, the more we're just reading the tea leaves.
Right off the bat, we've got some serious swell on the way. The first real shot of action is shaping up for Wednesday the 5th, but there's a catch – it's beefy. We're talking 12ft of southeast swell with a 15-second period. That's a lot of juice, and the combined energy is reading strong at 5361. The wind is a cross-offshore from the NE at 19 mph, which would normally have me licking my chops. But honestly, this is just too much for Onjuku. The model is saying the same thing – it's too big for the break. It's not going to be a friendly wave for the average punter; it's going to be a washing machine. The water temp is a touch above average at 81°, so it's a nice balmy day to watch.
Thursday the 6th sees the swell drop a bit to 7ft, still from the SSE with a 13-second period. The morning is looking clean, with a light ENE cross-offshore breeze at 9 mph. This is where it starts to get interesting for the experienced crew. The energy is moderate at 1969, and the conditions are described as excellent for experienced surfers. This is a proper standout – solid size, long period, and clean faces. This is the one to circle on the calendar if you know what you're doing. The afternoon goes a little cross, so the morning session is the go.
From Friday the 7th through the weekend, things get a bit lazy. The swell backs off to 5ft to 7ft, but the wind goes onshore or cross-onshore, and the surf gets a bit ragged. The energy drops into the weak to moderate range, between 905 and 1720. It's not terrible, but it's not worth getting excited about. We'll have some rideable waves, but it'll be a bit of a grovel.
Monday the 10th and Tuesday the 11th see a new pulse of energy, and this time the wind is offshore – a proper NNE breeze at 22 to 25 mph. The swell is 8ft to 8ft from the E/ENE. The energy is moderate, around 1963 and 1718. The problem? The wind is howling. It's a strong offshore, which will hold the waves up, but it's going to be a battle to get out the back. It's clean, but the conditions will be wild. This is for the fit and the brave, not for a casual paddle. On the 12th, the wind picks up even more, with a near-gale possible, and the surf quality just goes to the dogs.
The following week, from Wednesday the 12th through the 17th, is pretty grim. The swell drops off, the wind stays messy, and we're dealing with a lot of poor surf conditions and onshore slop. There's a lot of rain in the forecast too. It’s a real flat, junky spell. The energy readings are weak, mostly under 600. It's a good time to get the fishing gear out or work on your tan.
Now, we do have a light at the end of the tunnel. Around Tuesday the 18th and into Wednesday the 19th, the models are hinting at a proper long-period groundswell from the SSE. We're looking at periods of 16 seconds, which is very long. The energy starts to build again, hitting 1444 and climbing. On the 19th, the swell is up to 8ft to 10ft, but the wind is going to be the issue, coming onshore. It’s a bit of a tease.
But then, on Thursday the 20th, we might get something special. The forecast shows an 12ft swell from the SE with a 13-second period, and the energy is reading strong at 4674. The early call has a light SSW wind on it. If that holds, Onjuku could be on. However, like the 5th, this size is predicted to be too big for the break, and the conditions are unknown. It's far out, so treat it as a promising but very uncertain prospect. It's a long way off, so we just have to wait and see.
So, to sum it up: the clear standouts are the Thursday morning session on the 6th for the experienced rippers, and that far-off potential on the 20th. The rest is either too big and wild or just plain flat and messy. Keep an eye on the sky, and I'll see you out there.
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 5mm), mostly falling on Mon night. Warm (max 27°C on Sat morning, min 23°C on Sun night). Winds increasing (calm on Sat night, strong winds from the N by Mon night). | ||||||||||||||||||||
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 13 | SSE 12 | S 13 | S 13 | S 13 | S 13 | S 13 | S 13 | ESE 13 | ESE 14 | ESE 13 | ESE 13 | E 12 | E 12 | ENE 12 | ENE 11 | ENE 10 | E 11 |
Wave Graph | |||||||||||||||||||||
5330 | 4542 | 2795 | 1572 | 1360 | 1543 | 1391 | 1233 | 878 | 633 | 623 | 824 | 1138 | 1106 | 774 | 1556 | 1570 | 2348 | 1541 | 1250 | 1137 | |
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 | cross-on | glassy | 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 | — | — | — | — | — | — | — | — | — | — | — | — | — | 5 | 1 | 1 | 7 |
Temp °C | 25 | 25 | 25 | 28 | 28 | 26 | 28 | 28 | 25 | 27 | 27 | 25 | 27 | 26 | 24 | 25 | 25 | 24 | 25 | 25 | 24 |
Feels °C | 24 | 25 | 29 | 31 | 31 | 30 | 31 | 31 | 27 | 29 | 29 | 28 | 27 | 26 | 24 | 21 | 21 | 21 | 22 | 22 | 20 |
Swell 1 Height (m) Direction Period (s) | SE 15 | SE 14 | SE 13 | SSE 13 | SSE 12 | S 13 | S 13 | S 13 | S 13 | S 13 | S 13 | ESE 13 | ESE 14 | ESE 13 | ESE 13 | S 12 | E 12 | S 13 | S 12 | SSW 13 | E 11 |
5330 | 4542 | 2795 | 1572 | 1360 | 1543 | 1391 | 1233 | 878 | 633 | 623 | 824 | 1138 | 1106 | 774 | 137 | 1570 | 84 | 104 | 195 | 1137 | |
Swell 2 Height (m) Direction Period (s) | E 18 | E 18 | E 16 | ESE 10 | ESE 10 | ESE 10 | ESE 10 | ESE 10 | ESE 9 | ESE 9 | ESE 12 | S 12 | S 13 | S 12 | S 12 | SW 14 | S 12 | SW 14 | SW 14 | SW 13 | SSW 12 |
6 | 24 | 21 | 377 | 325 | 346 | 290 | 284 | 282 | 236 | 591 | 522 | 386 | 285 | 239 | 103 | 99 | 102 | 73 | 451 | 157 | |
Swell 3 Height (m) Direction Period (s) | E 18 | — | E 12 | E 16 | E 16 | E 15 | E 15 | E 15 | E 14 | E 14 | E 14 | — | SW 15 | SW 15 | SW 15 | SSW 11 | SW 14 | SSW 12 | — | — | SW 13 |
25 | — | 66 | 20 | 20 | 41 | 39 | 39 | 37 | 36 | 16 | — | 77 | 134 | 181 | 167 | 102 | 113 | — | — | 382 | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | ENE 5 | E 12 | NE 6 | ENE 12 | ENE 11 | ENE 10 | — |
— | — | — | — | — | — | — | — | — | — | — | — | — | — | 29 | 1556 | 165 | 2348 | 1541 | 1250 | — | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 78 | 56 | 0 | 0 | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 0 | 51 | 103 | 51 | 206 | 2120 | 200 | 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.











