
Surf Forecasts:
Onjuku surf forecast from 5 Sep 2026:
- Best quality surf: Tuesday 8 Sep, 6PM (local time) - 7ft (2.1m), 9s period, SSE swell with glassy winds.
- Most powerful swell: Monday 7 Sep, 12PM (local time) - 11ft (3.5m), 10s period, S swell with 2,625 kJ wave energy.
- Next surfable swell (1★+): Saturday 5 Sep, 12PM (local time) - 3.5ft (1.0m), 6s 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 Saturday (Sep 05) at 12PM. The primary swell is predicted to be 1.0m and 6s period with a secondary swell of 0.5m and 9s. Another secondary swell of 0.4m and 9s is also forecast. 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 10s and forecast to arrive on Monday (Sep 07) at 12PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.6m 6s period and expected on Sunday (Sep 06) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12PM (Sat 5th Sep) | 3.5ft (1.0m) 6s |
| Best Surf | 6PM (Tue 8th Sep) | 7ft (2.1m) 9s |
| Most Powerful | 12PM (Mon 7th Sep) | 11ft (3.5m) 10s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Righto, grab a drink, 'cause we're having a proper look at Onjuku for the next couple of weeks. I've gotta be straight with you: the start is a write-off. We've got a stretch of poor conditions from Saturday the 5th right through, and the real action doesn't even look like getting started until Monday the 14th. That's a solid week of flat or messy, wind-whipped nothing.
Let's break it down. Saturday the 5th and Sunday the 6th are just plain ugly – onshore winds, weak swell, rain, the works. The weekend is a right-off. Monday the 7th sees a big pulse of energy, but it's all onshore wind and stormy, with the combined energy hitting over 2000 (2054) on the Monday morning – that's strong to very strong energy but it's a mess. Not worth paddling out.
The wind keeps hammering us through the week. Tuesday the 8th has moderate swell around 7ft to 8ft from the SSE with a 10-second period, but the wind is cross-onshore and lumpy. That kind of size and messy wind is only for the die-hards, and even then, it's grim. Thursday the 10th finally sees the wind swing offshore, but the swell is short period (7 seconds) and the energy is only moderate (651). The waves will be weak and bumpy.
Now, we start to see a glimmer from Monday the 14th. The swell drops a bit to 5ft from the ESE, period bumps to 10 seconds, and the wind is cross-offshore. The conditions are described as marginal, but the energy is moderate (573). It's not a standout, but it's the first real chance to get wet without hating yourself. Tuesday the 15th morning actually shows "expect good surf conditions" – the wind is light cross-offshore from the ENE, swell is small at 2ft but with a very long period of 13 seconds from the East. That's proper groundswell energy (289). That's a good sign for the reefs and points, but beach breaks might find it a bit too straight. The water is 82°, which is about 2° warmer than average for this time of year – not a huge deal, but nice.
The real standout in this whole forecast falls on Thursday the 17th and Friday the 18th of September. On Thursday the 17th morning, we get offshore winds from the North at 16 mph, a clean 3ft swell from the NE with a 7-second period, and "improved" conditions, with moderate but clean energy (294). It's not huge, but it's clean. Then Friday the 18th morning is similar – offshore winds from the NNE, 4ft swell from the East at 8 seconds, and it's a "good surf conditions" call with clean waves (223). The wind will be offshore both mornings, and that's gold for Onjuku. The swell is small, so it'll be a longboard or funboard wave, but it'll be glassy and fun. Crowds are listed as "sometimes" here, so you might find a few others out, but with the small size, it shouldn't be a zoo. The optimum direction for this spot is SSE, so the East/NE swells aren't perfect direction-wise, but the clean conditions make it worth the paddle.
To be honest, the second week is quiet. After Friday, we fade back into small, cross-onshore dribble from the 19th onward. The 17th and 18th mornings are your best bet, and even then, it's a small, clean window. If you've got a log and are happy to scratch for knee-to-waist high, you'll be stoked. Otherwise, this 16-day window is a patience test. Keep an eye on the forecasts, because a run like this usually has to break sometime.
Rusty.
Short Range ForecastHeavy rain (total 252mm), heaviest during Sun night. Warm (max 27°C on Mon morning, min 22°C on Sat morning). Winds increasing (light winds from the ENE on Sat morning, strong winds from the S by Mon morning). | Days 4-6 Weather SummaryHeavy rain (total 51mm), heaviest during Thu afternoon. Warm (max 28°C on Wed morning, min 18°C on Thu night). Winds increasing (calm on Tue afternoon, strong winds from the NE by Thu afternoon). | ||||||||||||||||||||
Saturday 5 | Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | Friday 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) | S 10 | SSW 9 | ESE 8 | SSE 8 | E 7 | ESE 8 | SSE 9 | S 10 | SSE 10 | SSE 10 | SSE 10 | S 9 | S 8 | S 9 | S 9 | NE 7 | ENE 7 | ENE 8 | ENE 7 | ENE 6 | E 13 |
Wave Graph | |||||||||||||||||||||
47 | 28 | 24 | 13 | 487 | 1159 | 1604 | 2590 | 1393 | 1255 | 885 | 794 | 959 | 1184 | 533 | 342 | 344 | 356 | 121 | 107 | 92 | |
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-off | cross-on | on | on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-off | cross-off | cross-off | cross-off | off | off | off |
High Tide | 8:26PM1.30m | 4:09PM1.19m | 10:16PM1.23m | 3:44PM1.25m | 00:42AM1.25m | 3:57PM1.30m | 2:06AM1.33m | 4:14PM1.34m | 3:06AM1.40m | 4:32PM1.36m | 3:56AM1.45m | 4:50PM1.39m | |||||||||
Low Tide | 6:01AM0.34m | 6:12PM1.19m | 7:30AM0.27m | 8:17PM1.09m | 8:30AM0.20m | 8:59PM0.95m | 9:17AM0.17m | 9:34PM0.80m | 9:55AM0.18m | 10:07PM0.64m | 10:29AM0.24m | 10:40PM0.50m | |||||||||
5:13 | — | — | 5:13 | — | — | 5:13 | — | — | 5:15 | — | — | 5:16 | — | — | 5:16 | — | — | 5:16 | — | — | |
— | 6:00 | — | — | 5:59 | — | — | 5:58 | — | — | 5:57 | — | — | 5:54 | — | — | 5:53 | — | — | 5:52 | — | |
mm | 9 | 2 | — | 4 | 20 | 157 | 30 | 6 | 24 | 2 | 3 | 10 | 3 | 5 | 8 | 5 | 6 | 9 | 1 | 2 | 1 |
Temp °C | 22 | 23 | 23 | 24 | 23 | 26 | 27 | 27 | 27 | 26 | 26 | 27 | 28 | 28 | 23 | 21 | 21 | 21 | 18 | 19 | 20 |
Feels °C | 23 | 22 | 22 | 21 | 20 | 24 | 25 | 26 | 28 | 28 | 30 | 27 | 27 | 28 | 24 | 18 | 18 | 17 | 15 | 17 | 20 |
Swell 1 Height (m) Direction Period (s) | S 10 | SSW 9 | ESE 8 | SSE 8 | S 8 | NE 9 | E 8 | E 8 | SSE 10 | SSE 10 | SSE 10 | E 8 | E 9 | E 9 | S 9 | S 9 | S 9 | S 8 | S 8 | ENE 6 | ENE 5 |
47 | 28 | 24 | 13 | 19 | 172 | 450 | 279 | 1393 | 1255 | 885 | 29 | 27 | 13 | 533 | 264 | 150 | 65 | 31 | 64 | 47 | |
Swell 2 Height (m) Direction Period (s) | ESE 9 | ESE 9 | SSW 8 | SSW 8 | E 15 | NNE 12 | — | NNE 11 | E 9 | E 8 | E 19 | SSW 14 | E 17 | E 16 | ESE 16 | ESE 15 | ESE 15 | ESE 14 | E 14 | S 8 | E 13 |
27 | 26 | 24 | 7 | 4 | 15 | — | 12 | 175 | 86 | 7 | 20 | 23 | 21 | 49 | 42 | 73 | 68 | 104 | 28 | 92 | |
Swell 3 Height (m) Direction Period (s) | SE 9 | SE 6 | E 12 | SE 12 | ESE 11 | — | — | — | SE 10 | E 16 | E 19 | E 18 | NE 8 | NNE 8 | ESE 11 | SE 9 | SE 10 | — | SE 10 | E 14 | S 8 |
13 | 14 | 11 | 6 | 13 | — | — | — | 26 | 5 | 7 | 6 | 3 | 6 | 12 | 3 | 16 | — | 15 | 100 | 28 | |
Wind waves Height (m) Direction Period (s) | E 6 | E 5 | E 5 | ENE 6 | E 7 | ESE 8 | SSE 9 | S 10 | — | — | — | S 9 | S 8 | S 9 | NE 7 | NE 7 | ENE 7 | ENE 8 | ENE 7 | ENE 6 | N 4 |
75 | 32 | 70 | 186 | 487 | 1159 | 1604 | 2590 | — | — | — | 794 | 959 | 1184 | 321 | 342 | 344 | 356 | 121 | 107 | 30 | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 51 | 0 | 553 | 617 | 617 | 68 | 57 | 88 | 78 | 18 | 9 | 17 | 88 | 82 | 51 | 617 | 110 | 240 | 206 | 200 | 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.










