Surf Forecasts:
Onjuku surf forecast from 31 Aug 2026:
- Best quality surf: Tuesday 1 Sep, 6AM (local time) - 3ft (0.9m), 12s period, ESE swell with cross-offshore winds.
- Most powerful swell: Tuesday 8 Sep, 6AM (local time) - 5ft (1.5m), 10s period, SSE swell with 411 kJ wave energy.
- Next surfable swell (1★+): Tuesday 1 Sep, 6AM (local time) - 3ft (0.9m), 12s 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 Tuesday (Sep 01) at 6AM. The primary swell is predicted to be 0.9m and 12s period with a secondary swell of 1.0m and 8s. Another secondary swell of 1.2m and 7s 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 1.5m 10s and forecast to arrive on Tuesday (Sep 08) at 6AM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.5m 6s period and expected on Sunday (Sep 06) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Tue 1st Sep) | 3ft (0.9m) 12s |
| Best Surf | 6AM (Tue 1st Sep) | 3ft (0.9m) 12s |
| Most Powerful | 6AM (Tue 8th Sep) | 5ft (1.5m) 10s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s take a real good look at what Onjuku’s got cookin’ for the next couple of weeks. Gotta be honest with ya, it’s a tough start and a long wait for anything worth paddling out for.
For the first few days, we’re in a holding pattern. Tuesday the 1st and Wednesday the 2nd offer a tiny 3 ft swell out of the ESE, with weak combined wave energy (only 203 on Wednesday morning). It’s clean, glassy even on Wednesday morning with a slight air, but the swell’s just too inconsistent and small to get excited about. Through Thursday and into the weekend, things go a bit sideways – onshore winds and storms mess up the surface, and the swell stays small and weak. Honestly, it’s a bit of a write-off until the following week.
Now, hold onto your board. Monday the 9th is where it all goes off, but for the wrong reasons for most of us. We’ve got a pumping 13 ft groundswell out of the SE with a very long period of 13 seconds. The combined energy is huge at 5503, but this thing is just too damn big for Onjuku. That’s expert-only territory, and even then, it’s a mission. The wind stays cross-off, so it’ll be clean, but at this size, it’s more of a survival session than a fun one. Tuesday the 10th stays huge, but with onshore winds and storms, it’s a no-go.
The real standout, the one to circle on your calendar, is Wednesday the 11th. We’re still looking at a solid 12 ft swell from the SSE with a 11-second period, and combined energy of 4845. It’s still big – too big for beginners – but more manageable than the previous days. The wind is a moderate cross-shore, so the lineup will have some texture, but for a strong intermediate or expert, this is your best shot. Keep in mind this long-period groundswell can make it break a bit straight at the beach, so paddle smart.
After that, from Thursday the 12th through to the end of the forecast, it’s back to onshore gales and storms, with dropping swell and poor conditions. The water temp is about average for the time of year at Onjuku, nothing unusual there.
So, to sum it up: if you’re an expert, Wednesday the 11th is the session. For everyone else, it’s a long wait for a small window that never really opens for you this time.
Rusty.
Short Range ForecastModerate rain (total 13mm), heaviest on Thu night. Warm (max 28°C on Wed afternoon, min 22°C on Thu night). Wind will be generally light. | Days 4-6 Weather SummaryHeavy rain (total 104mm), heaviest during Sun night. Warm (max 23°C on Fri morning, min 20°C on Fri night). Winds decreasing (strong winds from the NE on Sun morning, calm by Sun night). | ||||||||||||||||||||
Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | Saturday 5 | Sunday 6 | Monday 7 | |||||||||||||||
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) | ESE 12 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | ESE 11 | ESE 10 | E 10 | E 10 | S 10 | S 9 | S 9 | S 8 | S 8 | SE 8 | ENE 6 | ENE 7 | ENE 6 | ENE 7 | E 7 | SSE 10 |
Wave Graph  | |||||||||||||||||||||
 kJ | 193 | 214 | 210 | 146 | 111 | 123 | 104 | 71 | 68 | 71 | 63 | 76 | 68 | 33 | 31 | 200 | 223 | 198 | 282 | 200 | 290 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | cross-off | glassy | on | on | on | cross-on | off | cross-off | cross-off | off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | off | cross-off |
High Tide | 6:31PM1.44m | 7:30AM1.23m | 6:53PM1.43m | 8:31AM1.12m | 7:17PM1.40m | 10:14AM1.02m | 7:46PM1.36m | 8:26PM1.30m | 4:09PM1.19m | 10:16PM1.23m | 3:44PM1.25m | 00:42AM1.25m | |||||||||
Low Tide | 12:27PM0.56m | 1:09AM0.32m | 12:52PM0.70m | 1:54AM0.31m | 1:12PM0.84m | 2:52AM0.34m | 1:18PM0.97m | 4:13AM0.36m | 6:01AM0.34m | 6:12PM1.19m | 7:30AM0.27m | 8:17PM1.09m | |||||||||
 | |  | |  |  | |  |  |  | |  |  |  |  |  | | | | | | |
 | 5:09 | — | — | 5:11 | — | — | 5:11 | — | — | 5:11 | — | — | 5:13 | — | — | 5:13 | — | — | 5:13 | — | — |
 | — | 6:06 | — | — | 6:05 | — | — | 6:04 | — | — | 6:01 | — | — | 6:00 | — | — | 5:59 | — | — | 5:58 | — |
mm | — | — | — | — | — | 1 | — | 3 | 9 | 11 | 14 | 15 | 9 | 2 | 2 | 3 | 2 | 46 | 10 | 1 | 10 |
Temp °C | 26 | 26 | 25 | 27 | 28 | 26 | 28 | 28 | 24 | 23 | 22 | 21 | 22 | 23 | 23 | 23 | 23 | 23 | 22 | 22 | 24 |
Feels °C | 27 | 28 | 27 | 30 | 31 | 29 | 30 | 31 | 26 | 24 | 23 | 20 | 22 | 22 | 21 | 19 | 19 | 21 | 24 | 22 | 25 |
Swell 1 Height (m) Direction Period (s) | ENE 7 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | ESE 11 | ESE 10 | S 8 | SSE 6 | SE 7 | SE 7 | SE 6 | S 8 | S 8 | SE 8 | SE 8 | SE 8 | SE 7 | SSE 7 | E 7 | SSE 10 |
| kJ | 86 | 214 | 210 | 146 | 111 | 123 | 104 | 69 | 55 | 65 | 54 | 70 | 68 | 33 | 31 | 23 | 14 | 12 | 90 | 200 | 290 |
Swell 2 Height (m) Direction Period (s) | ESE 12 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | S 8 | E 10 | E 10 | S 10 | S 9 | S 9 | SE 7 | SE 7 | SSW 8 | SSW 8 | SSW 8 | SE 11 | SE 11 | SSE 7 | E 7 |
| kJ | 193 | 59 | 56 | 37 | 37 | 26 | 36 | 71 | 68 | 71 | 63 | 76 | 38 | 27 | 20 | 12 | 6 | 19 | 19 | 134 | 127 |
Swell 3 Height (m) Direction Period (s) | SSW 8 | SSW 9 | SSW 8 | SSW 8 | SSW 8 | S 8 | ENE 7 | SE 5 | S 8 | E 9 | E 9 | E 9 | ESE 9 | ESE 9 | ESE 8 | SE 10 | SE 11 | SSW 9 | ESE 7 | — | — |
| kJ | 14 | 15 | 14 | 14 | 23 | 36 | 15 | 11 | 21 | 59 | 41 | 40 | 26 | 25 | 23 | 4 | 5 | 8 | 59 | — | — |
Wind waves Height (m) Direction Period (s) | — | — | NE 7 | — | — | — | S 3 | — | WSW 4 | — | ENE 2 | NNE 3 | NE 5 | NE 6 | ENE 6 | ENE 6 | ENE 7 | ENE 6 | ENE 7 | NNW 4 | NNE 7 |
| kJ | — | — | 71 | — | — | — | 1 | — | 18 | — | 1 | 6 | 42 | 101 | 132 | 200 | 223 | 198 | 282 | 9 | 96 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 56 | 16 | 51 | 0 | 0 | 9 | 9 | 9 | 9 | 51 | 51 | 617 | 617 | 617 | 617 | 295 | 295 | 553 | 295 | 571 | 295 |
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.
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