Surf Forecasts:
Onjuku surf forecast from 1 Sep 2026:
- Best quality surf: Wednesday 2 Sep, 9AM (local time) - 3ft (0.9m), 10s period, ESE swell with glassy winds.
- Most powerful swell: Tuesday 8 Sep, 9PM (local time) - 10ft (3.0m), 12s period, SSE swell with 2,400 kJ wave energy.
- Next surfable swell (1★+): Wednesday 2 Sep, 9AM (local time) - 3ft (0.9m), 10s 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 Wednesday (Sep 02) at 9AM. The primary swell is predicted to be 0.9m and 10s period with a secondary swell of 0.7m and 7s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 3.0m 12s and forecast to arrive on Tuesday (Sep 08) at 9PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 4s period and expected on Friday (Sep 04) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Wed 2nd Sep) | 3ft (0.9m) 10s |
| Best Surf | 9AM (Wed 2nd Sep) | 3ft (0.9m) 10s |
| Most Powerful | 9PM (Tue 8th Sep) | 10ft (3.0m) 12s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s size up the surf situation at Onjuku.
It’s a slow burner. First few days are small and messy, but the back half of the two weeks pulls a couple of absolute crackers if you’ve got the nerve.
September 1st kicks off with a knee-high 3ft wave from the east-southeast at 11 seconds. Wind’s side-shore, so it’s a bit grovelly. Water’s 80°F, right on average for the time of year. The real first chance for a clean wave comes Wednesday morning, September 2nd—still only 3ft, but the wind goes glassy. Combined energy is weak at 208, so it’s a small-wave board day.
Thursday and Friday the 3rd and 4th give us a brief window: Friday afternoon shows a 4ft wave from the south with a gentle offshore wind and clean conditions. Energy is moderate at 335. Not huge, but workable.
Then we hit the doldrums. From September 5th through the 8th, the wind is cranking 25-30 mph and the sea state is ugly. Swell grows to 6-7ft by the 8th, but it’s onshore and lumpy. Energy hits over 1000 (1102, 1195), but the quality is garbage. This is more for kite surfers than paddle surfers.
Now, mark your calendar. Wednesday September 9th morning is the one. Swell pumps to a solid 10ft from the south-southeast, period a clean 11 seconds, and the wind is dead calm—glassy. Combined energy is massive at 1909. This is a serious groundswell. With that height and period, it’s for experts only. Onjuku is open to that SSE direction, so it’ll be stacking up proper. Crowds are a possibility, so get there early.
Thursday September 10th morning keeps the magic going: another 10ft from the SSE, period stretching to 12 seconds, and a light offshore/cross-off wind keeping things smooth. Energy is 2255. Another day for the brave.
After that, the wind shifts onshore and the quality drops off, even though the swell hangs around. From September 13th to the 16th, we get smaller surf (3-5ft) but with very long periods up to 17 seconds. That kind of swell can be tricky at a beach break—tends to jack up and close out. The wind stays clean and cross-off, so it’s a pretty sight, but the shape will be better on a point or reef.
Best call: hit September 9th and 10th hard for the big, clean groundswell. Everything else is either small, blown, or too long-period to do much at Onjuku.
Rusty.
Short Range ForecastHeavy rain (total 134mm), heaviest during Fri morning. Warm (max 28°C on Wed morning, min 21°C on Fri morning). Wind will be generally light. | Days 5-7 Weather SummaryHeavy rain (total 194mm), heaviest during Sat afternoon. Warm (max 25°C on Mon morning, min 20°C on Fri night). Winds increasing (light winds from the N on Fri afternoon, strong winds from the NNE by Sat morning). | |||||||||||||||||||
Tue 1 | Wednesday 2 | Thursday 3 | Friday 4 | Saturday 5 | Sunday 6 | Monday 7 | ||||||||||||||
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 11 | ESE 11 | ESE 10 | E 10 | E 11 | E 10 | E 10 | E 10 | SE 7 | S 8 | S 9 | S 9 | E 6 | E 7 | E 7 | E 8 | ESE 8 | E 8 | E 8 | S 12 |
Wave Graph | ||||||||||||||||||||
214 | 210 | 146 | 200 | 88 | 98 | 71 | 68 | 109 | 200 | 165 | 99 | 139 | 262 | 411 | 463 | 356 | 373 | 373 | 827 | |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | glassy | cross-on | on | on | cross-on | off | off | off | cross-off | off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-on | cross-on | cross-on |
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 | 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 | |||||||||
— | — | 5:11 | — | — | 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 | 6 | 3 | 68 | 56 | 7 | 13 | 12 | 33 | 23 | 6 | 25 | 55 | 20 | 45 | 22 |
Temp °C | 27 | 26 | 28 | 28 | 26 | 27 | 27 | 24 | 22 | 21 | 21 | 20 | 21 | 22 | 23 | 23 | 24 | 25 | 25 | 27 |
Feels °C | 29 | 29 | 31 | 30 | 30 | 30 | 30 | 26 | 21 | 21 | 21 | 15 | 18 | 20 | 18 | 20 | 26 | 24 | 23 | 23 |
Swell 1 Height (m) Direction Period (s) | ESE 11 | ESE 11 | ESE 10 | E 10 | E 8 | E 10 | E 10 | SE 7 | SE 7 | S 8 | S 9 | S 9 | S 8 | SSW 8 | SSW 9 | SSW 9 | ESE 8 | E 8 | E 8 | S 12 |
214 | 210 | 146 | 200 | 55 | 98 | 71 | 52 | 109 | 200 | 165 | 99 | 50 | 23 | 16 | 8 | 356 | 373 | 373 | 827 | |
Swell 2 Height (m) Direction Period (s) | ENE 7 | ENE 7 | ENE 7 | SSW 8 | E 11 | E 7 | S 8 | E 10 | S 10 | SE 8 | SE 7 | SE 7 | ENE 13 | ENE 11 | SE 14 | E 15 | ENE 10 | S 7 | SSE 9 | ENE 8 |
59 | 69 | 48 | 23 | 88 | 23 | 51 | 68 | 98 | 94 | 42 | 43 | 33 | 47 | 8 | 4 | 36 | 27 | 138 | 270 | |
Swell 3 Height (m) Direction Period (s) | SSW 9 | SSW 8 | SSW 8 | E 13 | S 8 | S 8 | SE 6 | S 8 | E 9 | E 9 | ENE 5 | ESE 9 | NE 11 | SE 12 | SE 12 | SE 14 | SSW 9 | SE 11 | S 12 | SE 10 |
15 | 14 | 14 | 52 | 36 | 36 | 17 | 35 | 42 | 41 | 15 | 26 | 33 | 6 | 6 | 8 | 8 | 5 | 49 | 16 | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | SSE 3 | — | — | — | NE 4 | NE 5 | NE 5 | ENE 5 | E 6 | E 7 | E 7 | E 8 | — | NE 8 | NE 8 | ENE 8 |
— | — | — | — | 1 | — | — | — | 39 | 38 | 19 | 66 | 139 | 262 | 411 | 463 | — | 203 | 173 | 381 | |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 51 | 56 | 0 | 9 | 9 | 9 | 9 | 0 | 12 | 0 | 15 | 295 | 295 | 553 | 617 | 536 | 536 | 617 | 617 | 554 |
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.











