Surf Forecasts:
Onjuku surf forecast from 6 Sep 2026:
- Best quality surf: Wednesday 9 Sep, 9PM (local time) - 7ft (2.2m), 9s period, S swell with offshore winds.
- Most powerful swell: Tuesday 8 Sep, 3AM (local time) - 10ft (3.0m), 9s period, S swell with 1,468 kJ wave energy.
- Next surfable swell (1★+): Wednesday 9 Sep, 9PM (local time) - 7ft (2.2m), 9s period with S 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 09) at 9PM. The primary swell is predicted to be 2.2m and 9s period with a secondary swell of 0.2m and 16s. The wind is predicted to be 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 Tuesday (Sep 08) at 3AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.2m 6s period and expected on Wednesday (Sep 09) at 9PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Wed 9th Sep) | 7ft (2.2m) 9s |
| Best Surf | 9PM (Wed 9th Sep) | 7ft (2.2m) 9s |
| Most Powerful | 3AM (Tue 8th Sep) | 10ft (3.0m) 9s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here. Let's cut through it.
We’ve got a rough start at Onjuku. Monday the 7th through Wednesday the 9th is all stormy, windy junk. Lots of energy in the water, but it's onshore and messy. Don't even bother.
Thursday 10th September is your first chance. The swell drops to about 4ft from the S, and the wind goes offshore from the NNE. It's clean, but a bit choppy from the breeze. The water's about normal temp for the season. It's a go, but not the highlight.
The big one is Tuesday 22nd September. That's the day. A long-period groundswell from the SE, 17 seconds between waves, pushing 5ft. The energy reading is off the charts at 1556. And the wind? Dead calm. Glassy. This is a proper, powerful, clean swell. It's for experienced hands only – that long period can make a beach break weird, but the conditions are perfect. If you can handle it, that's your session.
From the 11th to the 21st, it's small but clean. A few days like the 12th and 16th look glassy but tiny, with waves around 2ft. Fine for a longboard, but small.
So, the plan: wait out the first week, grab a few small clean days, and then go all-in on the 22nd for that glassy, powerful groundswell.
Rusty.
Short Range ForecastHeavy rain (total 102mm), heaviest during Sun night. Warm (max 29°C on Wed morning, min 24°C on Sun night). Winds decreasing (strong winds from the SE on Sun night, light winds from the SSW by Tue afternoon). | Days 5-7 Weather SummaryModerate rain (total 12mm), heaviest on Wed night. Warm (max 25°C on Sat morning, min 20°C on Wed night). Winds decreasing (fresh winds from the NNE on Thu afternoon, calm by Fri night). | ||||||||||||||||||
Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | Friday 11 | Saturday 12 | ||||||||||||||
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 8 | S 9 | S 9 | S 9 | S 9 | S 9 | S 9 | S 8 | S 9 | S 9 | S 8 | S 8 | S 8 | E 14 | E 14 | E 14 | E 14 | E 13 | E 13 |
Wave Graph  | |||||||||||||||||||
 kJ | 1000 | 1183 | 1361 | 1463 | 726 | 700 | 731 | 670 | 1005 | 539 | 201 | 130 | 74 | 106 | 100 | 136 | 134 | 128 | 130 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | off | cross-off | cross-off | cross-off | off | cross-off | glassy | cross-on | cross-off |
High Tide | 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 | 4:41AM1.47m | 5:08PM1.41m | |||||||
Low Tide | 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 | 10:59AM0.34m | 11:13PM0.38m | |||||||
 |  |  | | | | | | |  |  | |  |  |  |  | | | | |
 | — | 5:13 | — | — | 5:15 | — | — | 5:16 | — | — | 5:16 | — | — | 5:16 | — | — | 5:18 | — | — |
 | — | — | 5:58 | — | — | 5:57 | — | — | 5:54 | — | — | 5:53 | — | — | 5:52 | — | — | 5:51 | — |
mm | 67 | 10 | 5 | 2 | 2 | 4 | 6 | 3 | 3 | 8 | 2 | 2 | — | — | — | — | — | — | — |
Temp °C | 26 | 27 | 27 | 27 | 28 | 28 | 27 | 29 | 28 | 24 | 22 | 21 | 21 | 22 | 22 | 22 | 25 | 25 | 24 |
Feels °C | 25 | 26 | 27 | 27 | 30 | 31 | 29 | 29 | 28 | 28 | 20 | 19 | 19 | 23 | 23 | 25 | 28 | 28 | 27 |
Swell 1 Height (m) Direction Period (s) | S 9 | E 8 | E 8 | S 9 | S 9 | SSE 9 | S 9 | NE 8 | NE 8 | S 9 | S 8 | S 8 | S 8 | ENE 6 | S 8 | E 14 | E 14 | E 13 | SE 9 |
| kJ | 175 | 316 | 230 | 1041 | 726 | 528 | 493 | 11 | 11 | 539 | 201 | 130 | 74 | 51 | 40 | 136 | 134 | 128 | 62 |
Swell 2 Height (m) Direction Period (s) | S 9 | SE 11 | E 18 | E 8 | E 9 | E 8 | E 8 | ESE 10 | E 16 | ESE 16 | ESE 15 | ESE 15 | ESE 14 | S 8 | E 14 | NE 6 | ESE 9 | ESE 9 | E 13 |
| kJ | 175 | 5 | 6 | 140 | 71 | 51 | 31 | 10 | 21 | 49 | 42 | 72 | 67 | 54 | 100 | 15 | 31 | 53 | 130 |
Swell 3 Height (m) Direction Period (s) | NE 12 | NE 11 | E 18 | NE 11 | E 16 | SE 10 | SE 10 | E 17 | E 16 | E 16 | SE 9 | SE 9 | SE 9 | E 14 | ESE 10 | S 7 | NE 6 | S 7 | NE 6 |
| kJ | 23 | 31 | 6 | 4 | 5 | 16 | 15 | 23 | 46 | 43 | 14 | 23 | 22 | 106 | 36 | 27 | 14 | 17 | 9 |
Wind waves Height (m) Direction Period (s) | ESE 8 | S 9 | S 9 | S 9 | — | S 9 | S 9 | S 8 | S 9 | NE 7 | NE 7 | ENE 7 | ENE 6 | — | NE 6 | — | — | ESE 3 | — |
| kJ | 1000 | 1183 | 1361 | 1463 | — | 700 | 731 | 670 | 1005 | 215 | 122 | 62 | 58 | — | 31 | — | — | 2 | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 617 | 200 | 295 | 101 | 57 | 17 | 57 | 88 | 71 | 9 | 0 | 51 | 51 | 22 | 0 | 0 | 0 | 9 | 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.
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