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: Monday 7 Sep, 3PM (local time) - 10ft (3.0m), 9s period, ENE swell with 1,494 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 7s. 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 3.0m 9s and forecast to arrive on Monday (Sep 07) 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 Saturday (Sep 05) at 6PM.
| 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 | 3PM (Mon 7th Sep) | 10ft (3.0m) 9s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here, and I've got the skinny on the next couple of weeks at Onjuku. Let's be real, it's a slow start, but there's a bit of a pulse later on. We're looking at a stretch of mostly small, messy surf, so you gotta pick your moments.
The water's sitting at about 81°, which is a touch warmer than normal for this time of year – not a bad thing for a late summer session.
First up, the immediate outlook is pretty grim. Monday the 31st is a write-off with a weak 4ft NE windswell and a short 6-second period. The energy is weak (246), and it's cross-offshore, but the conditions are just poor. We then hit a few days of small, inconsistent surf. Tuesday morning the 1st of September sees a cleaner 3ft ESE swell, but it's a long period (12 seconds) for a beach break, so it might be a bit too straight and fat. Still, the energy is moderate (324) and the wind is a gentle cross-off, so it's the best of a bad bunch.
Wednesday the 2nd of September morning is the real standout early on. The wind goes glassy, and we've got a clean 3ft ESE swell with a 10-second period. The combined energy is moderate (206), and it's the only truly glassy window we see for a while. It's small, but it'll be clean. After that, it's back to onshore slop and a few thunderstorms. We've got a solid gap of poor conditions from Thursday the 3rd right through the weekend.
Now, things get interesting around the 5th and 6th of September. The swell kicks up, but it's all windswell. Saturday the 5th sees 7ft of E swell with a short 7-second period and strong cross-offshore winds. The energy jumps to strong (442 to 540), but it's a messy, bumpy cleanup. Then Sunday the 6th brings even more size, 7ft to 8ft from the ENE, with massive energy readings (1023 to 1133). The wind is still strong cross-off, so it's going to be a powerful, bumpy, and challenging paddle. This is more for the experienced crew.
Monday the 7th of September is a real standout in the long-range, but it's for experts only. We're looking at 8ft of ENE swell in the morning, and the wind swings offshore from the north at 25 mph. The energy is off the charts at 2091. The description says it's "strong offshore and clean but hard to paddle into," which is exactly what it sounds like – big, powerful, and glassy walls, but you'll be fighting the wind to get out. The afternoon sees a shift to a 7ft SSE swell with a longer 12-second period, and again, strong offshore winds. The energy is even higher at 2332. If you're a charger and the wind plays ball, this is the window.
The rest of the second week settles back down. Tuesday the 8th and Wednesday the 9th offer some cleaner, more manageable 5ft to 6ft SSE swells with moderate winds, but the energy is moderate to strong. Then we get another messy spell from the 10th of September onward with strong onshore winds from the south and southeast, making the 8ft swell on the 10th a bumpy, lumpy mess. The 13th and 14th see a drop back to 3ft to 5ft, but the onshore cross-wind will keep it chopped up.
So, to sum it up: the best bet for a clean, small wave this week is Wednesday morning the 2nd of September. The big, raw, powerful, and properly offshore action is for experts only on Monday the 7th of September. Everything else is either too small, too windy, or too messy.
Rusty.
Short Range ForecastLight rain (total 2mm), mostly falling on Thu morning. Warm (max 28°C on Thu afternoon, min 23°C on Mon night). Wind will be generally light. | Days 5-7 Weather SummaryHeavy rain (total 176mm), heaviest during Fri night. Warm (max 24°C on Thu night, min 19°C on Fri afternoon). Winds increasing (moderate winds from the NE on Thu night, strong winds from the NE by Sun afternoon). | ||||||||||||||||||
Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | Saturday 5 | Sunday 6 | ||||||||||||||
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 12 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | ESE 11 | ESE 10 | E 10 | E 10 | S 10 | S 10 | SE 7 | SE 7 | ENE 6 | ENE 7 | ENE 8 | ENE 8 | E 9 |
Wave Graph | |||||||||||||||||||
138 | 193 | 173 | 210 | 146 | 111 | 123 | 104 | 71 | 68 | 75 | 67 | 65 | 44 | 107 | 316 | 534 | 636 | 943 | |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | cross-off | off | cross-off | cross-on | cross-on | on | cross-on | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off |
High Tide | 6:41AM1.32m | 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 | ||||||||
Low Tide | 00:30AM0.36m | 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 | ||||||||
— | 5:09 | — | — | 5:11 | — | — | 5:11 | — | — | 5:11 | — | — | 5:13 | — | — | 5:13 | — | — | |
6:07 | — | 6:06 | — | — | 6:05 | — | — | 6:04 | — | — | 6:01 | — | — | 6:00 | — | — | 5:59 | — | |
mm | — | — | — | — | — | — | — | 2 | — | 8 | 18 | 35 | 92 | 20 | 2 | 1 | — | — | 3 |
Temp °C | 24 | 26 | 26 | 24 | 27 | 27 | 26 | 27 | 28 | 24 | 22 | 20 | 20 | 21 | 22 | 23 | 24 | 24 | 23 |
Feels °C | 24 | 27 | 27 | 25 | 30 | 30 | 30 | 30 | 31 | 24 | 22 | 17 | 16 | 19 | 19 | 20 | 20 | 19 | 18 |
Swell 1 Height (m) Direction Period (s) | ESE 12 | ESE 12 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | ESE 11 | ESE 10 | E 10 | SE 7 | SE 7 | SE 7 | SE 7 | SE 7 | SE 8 | SE 12 | SSE 10 | SSE 10 | SSE 11 |
138 | 193 | 173 | 210 | 146 | 111 | 123 | 104 | 71 | 44 | 75 | 51 | 65 | 44 | 24 | 23 | 69 | 114 | 183 | |
Swell 2 Height (m) Direction Period (s) | E 11 | SSW 8 | SSW 9 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | S 8 | S 8 | E 10 | S 10 | E 9 | S 9 | SSW 9 | SSW 8 | SSW 8 | SSW 9 | E 12 | SSE 11 |
37 | 14 | 15 | 64 | 43 | 37 | 26 | 50 | 51 | 68 | 68 | 57 | 41 | 25 | 24 | 7 | 8 | 12 | 78 | |
Swell 3 Height (m) Direction Period (s) | SSW 9 | ESE 15 | SSE 10 | SSW 8 | SSW 8 | SSW 8 | S 8 | E 6 | SE 6 | SSW 12 | E 9 | S 10 | E 9 | ESE 9 | ESE 9 | ENE 12 | SW 11 | ENE 12 | SSW 10 |
16 | 21 | 10 | 14 | 14 | 23 | 36 | 25 | 23 | 45 | 42 | 67 | 40 | 17 | 26 | 15 | 29 | 14 | 10 | |
Wind waves Height (m) Direction Period (s) | NE 7 | ENE 7 | ENE 7 | NE 7 | — | — | — | — | — | NE 5 | — | NE 5 | NE 3 | ENE 6 | ENE 6 | ENE 7 | ENE 8 | ENE 8 | E 9 |
109 | 86 | 81 | 86 | — | — | — | — | — | 25 | — | 3 | 4 | 87 | 107 | 316 | 534 | 636 | 943 | |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 56 | 56 | 0 | 51 | 0 | 0 | 9 | 9 | 23 | 9 | 45 | 51 | 51 | 631 | 617 | 617 | 617 | 536 | 557 |
Best forecast wave conditions in Chiba | |||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||
Header Global | |||||||||||||||||||
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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.











