Surf Forecasts:
Onjuku surf forecast from 24 Aug 2026:
- Best quality surf: Thursday 27 Aug, 9PM (local time) - 2.5ft (0.7m), 13s period, E swell with cross-offshore winds.
- Most powerful swell: Monday 24 Aug, 6PM (local time) - 6ft (1.9m), 15s period, SSE swell with 1,559 kJ wave energy.
- Next surfable swell (1★+): Thursday 27 Aug, 9PM (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 9PM. The primary swell is predicted to be 0.7m and 13s period with a secondary swell of 0.8m and 9s. 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 1.9m 15s and forecast to arrive on Monday (Aug 24) at 6PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.9m 5s period and expected on Saturday (Aug 29) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Thu 27th Aug) | 2.5ft (0.7m) 13s |
| Best Surf | 9PM (Thu 27th Aug) | 2.5ft (0.7m) 13s |
| Most Powerful | 6PM (Mon 24th Aug) | 6ft (1.9m) 15s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s have a good hard look at what’s coming our way at Onjuku. I gotta be straight with you – the next week and a half is a tough stretch. We’ve got a serious gap in quality surf coming up, so don’t get your hopes up too high until we hit the end of the forecast period.
The story for the next week or so is pretty grim. From Monday the 24th of August onwards, it’s a whole lot of cross-onshore wind messing things up. The wave energy is moderate at best, but the wind just kills the quality. Monday morning starts off with a 3ft SSE swell, but it’s got a light cross-onshore breeze on it, so it’s not clean. The wave energy is only 944, so nothing special. That afternoon and into Tuesday and Wednesday, the wind picks up to a fresh breeze, making for lumpy, choppy conditions. The swell height bumps up to around 5 to 6ft, but with that wind, it’s just a mess. Not a good look for a paddle surf.
Thursday and Friday don’t offer any relief either, just more of the same – moderate to fresh cross-onshore winds with messy, poor surf conditions. The combined energy drops off a bit, sitting in the low hundreds, which tells you how weak and wind-affected it all is. There’s a solid 9-day stretch here where the best you can hope for is “surfable but very ordinary,” and that’s being generous. Honestly, if you’re a kiter, the strong cross-onshore winds on Monday the 25th at 18 mph and Wednesday the 26th at the same speed might look more interesting than anything for a surfboard.
We do get a slight window on Saturday the 29th and Sunday the 30th of August. The wind finally turns offshore or cross-offshore, and the conditions clean up. But the swell is tiny – only 2ft to 2ft – and the energy is weak, down around 128-187. It’s clean, but you’ll be working hard for small, weak waves. Then we’re back into poor conditions for Monday the 31st and Tuesday the 1st of September.
Now, look ahead. The real standout, and I mean the *only* standout in this whole 16-day window, is shaping up for a few days out. Wednesday the 2nd of September shows some promise. The afternoon session has a light 3ft swell from the ESE with a 10-second period and a gentle cross-offshore breeze. The conditions are forecast to be clean. The energy is low at 216, so it’s not a big day, but it’s the first time in a long time we get genuinely “good surf conditions” in the data.
The next big one to circle on your calendar is Saturday the 5th of September. The morning is where it’s at. We get a solid 6ft ENE windswell with a short 9-second period, but the wind is cross-off and the conditions are clean. The combined energy jumps to 1050, which is a moderate, punchy amount of energy for a beach break. That’s your best bet for some decent, clean waves, even if the short period will make it a little sectiony. It’s the biggest, cleanest swell of the whole run. But keep in mind, 6ft is pushing it for beginners.
After that, Sunday the 6th of September gets hammered by a strong breeze with onshore winds, and it falls apart again. The rest of the second week just fades back into poor conditions with moderate cross-onshore winds and weak energy.
So, bottom line: the first week is largely a washout. Saturday the 5th of September morning at Onjuku is the only true standout. It’s not perfect, but it’s the cleanest, biggest swell we’re going to see. The rest is just waiting and hoping the forecasts change for the better. Stay salty, and keep an eye on that Saturday.
Rusty
Short Range ForecastMostly dry. Warm (max 30°C on Wed morning, min 26°C on Mon night). Winds increasing (light winds from the SSW on Mon morning, fresh winds from the SW by Tue afternoon). | Days 4-6 Weather SummaryHeavy rain (total 22mm), heaviest during Thu night. Warm (max 29°C on Thu morning, min 23°C on Thu night). Mainly fresh winds. | ||||||||||||||||||||
Monday 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | |||||||||||||||
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) | SSE 18 | SSE 16 | SSE 13 | SSE 13 | SSE 12 | SSE 10 | S 12 | SSW 12 | SSW 6 | SSE 10 | E 13 | E 13 | SSW 10 | E 12 | SW 6 | E 11 | E 11 | E 11 | E 12 | E 12 | E 12 |
Wave Graph | |||||||||||||||||||||
459 | 1634 | 781 | 1025 | 658 | 241 | 180 | 160 | 84 | 123 | 173 | 163 | 226 | 115 | 124 | 91 | 62 | 61 | 95 | 139 | 134 | |
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-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-off | cross-on | cross-on | cross-on | off | cross-off | cross-off | cross-off | cross-off | glassy |
High Tide | 4:19PM1.20m | 1:32AM1.23m | 4:27PM1.25m | 2:31AM1.30m | 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 | ||||||||
Low Tide | 8:48PM1.04m | 9:08AM0.28m | 9:22PM0.95m | 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 | ||||||||
5:03 | — | — | 5:05 | — | — | 5:05 | — | — | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — | 5:07 | — | — | |
— | 6:16 | — | — | 6:15 | — | — | 6:14 | — | — | 6:13 | — | — | 6:12 | — | — | 6:09 | — | — | 6:08 | — | |
mm | — | — | — | — | — | — | — | — | — | — | 1 | 10 | — | — | 1 | 4 | 6 | — | — | — | — |
Temp °C | 28 | 28 | 26 | 28 | 28 | 27 | 30 | 29 | 27 | 29 | 29 | 26 | 28 | 28 | 26 | 27 | 26 | 24 | 26 | 26 | 25 |
Feels °C | 30 | 29 | 28 | 28 | 28 | 27 | 32 | 30 | 28 | 29 | 29 | 31 | 28 | 29 | 29 | 31 | 30 | 27 | 28 | 29 | 29 |
Swell 1 Height (m) Direction Period (s) | SSE 12 | SSE 16 | SSE 13 | SSE 13 | SSE 12 | SSE 10 | SSE 9 | SSE 9 | SSE 9 | SSW 6 | S 10 | S 9 | S 8 | E 12 | SSW 6 | S 8 | E 11 | E 11 | E 12 | E 12 | E 12 |
226 | 1634 | 781 | 1025 | 658 | 241 | 153 | 121 | 84 | 47 | 161 | 111 | 91 | 103 | 70 | 43 | 62 | 61 | 95 | 139 | 134 | |
Swell 2 Height (m) Direction Period (s) | SSE 18 | ESE 12 | SSE 16 | ESE 14 | ESE 13 | S 12 | S 12 | SSW 12 | SSW 12 | SSE 10 | E 13 | E 13 | E 12 | SSE 10 | E 12 | E 11 | SSW 8 | SSW 8 | SSW 8 | SSW 8 | ENE 6 |
459 | 109 | 653 | 198 | 181 | 217 | 180 | 160 | 81 | 123 | 173 | 163 | 148 | 19 | 99 | 91 | 36 | 24 | 24 | 22 | 10 | |
Swell 3 Height (m) Direction Period (s) | SSE 15 | ESE 8 | E 11 | E 11 | — | ESE 13 | ESE 12 | ESE 12 | E 12 | E 11 | S 10 | SSE 10 | SSE 9 | SE 15 | SSE 10 | SE 11 | SE 11 | SE 10 | SE 10 | SE 10 | SE 10 |
259 | 38 | 85 | 84 | — | 176 | 117 | 113 | 70 | 59 | 34 | 37 | 35 | 8 | 18 | 30 | 30 | 27 | 26 | 26 | 25 | |
Wind waves Height (m) Direction Period (s) | — | SW 8 | SSW 4 | SW 4 | SSW 4 | SSW 5 | SW 5 | SSW 5 | SSW 6 | SW 5 | — | — | SSW 10 | SSW 6 | SW 6 | NE 4 | NE 5 | NE 5 | ENE 4 | ENE 5 | — |
— | 55 | 8 | 18 | 35 | 44 | 27 | 40 | 71 | 80 | — | — | 226 | 115 | 124 | 14 | 37 | 17 | 13 | 17 | — | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 9 | 583 | 88 | 88 | 240 | 88 | 15 | 598 | 18 | 18 | 40 | 51 | 18 | 18 | 2 | 0 | 0 | 0 | 2 | 0 | 0 |
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.











