
Surf Forecasts:
Onjuku surf forecast from 8 Aug 2026:
- Best quality surf: Sunday 9 Aug, 9AM (local time) - 5.5ft (1.7m), 13s period, ESE swell with glassy winds.
- Most powerful swell: Saturday 15 Aug, 6PM (local time) - 8ft (2.5m), 10s period, E swell with 1,345 kJ wave energy.
- Next surfable swell (1★+): Sunday 9 Aug, 9AM (local time) - 5.5ft (1.7m), 13s 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 Sunday (Aug 09) at 9AM. The primary swell is predicted to be 1.7m and 13s period with a secondary swell of 0.8m and 10s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 2.5m 10s and forecast to arrive on Saturday (Aug 15) at 6PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.2m 5s period and expected on Thursday (Aug 13) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Sun 9th Aug) | 5.5ft (1.7m) 13s |
| Best Surf | 9AM (Sun 9th Aug) | 5.5ft (1.7m) 13s |
| Most Powerful | 6PM (Sat 15th Aug) | 8ft (2.5m) 10s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let's have a look at what's on the menu for Onjuku over the next couple of weeks. We've got a real mixed bag coming our way, with a solid run of waves bookending the period and a few quieter days in between.
We kick off this Sunday the 9th of August with some proper energy in the water. There's a 6ft swell pushing in from the ESE with a solid 13-second period – that's a nice groundswell. The combined energy is pumping at (1131), so there's plenty of push. Early morning, the wind is glassy from the ENE at just 3 mph, making for clean, lined-up sets. This is excellent for experienced surfers, and with the water temp at a balmy 80°F, which is bang on average for this time of year, it's a real treat. The afternoon sees the wind pick up and go onshore a bit, so get your session in early. This Sunday morning is one of the true standouts.
Monday the 10th steps up in size to 7ft but the wind cranks up to 19 mph from the NNE, staying clean but getting pretty strong. It's still surfable for those with a bit of paddle power. Tuesday the 11th morning looks magic again, with a clean 7ft from the ENE and a nice 10-second period, all under a light 6 mph offshore wind from the north. The energy is massive at (1514). This is another standout morning – get on it. The afternoon goes a bit sloppy with a cross-onshore wind.
Wednesday the 12th drops right off in size to 4ft, and the energy falls away to (358). It's clean but small. Thursday the 13th sees a bit of a rebound to 5ft with clean conditions and moderate energy (515) – a decent, fun-sized day. Friday the 14th and Saturday the 15th hold at around 6ft, mostly clean in the mornings, but with that ENE swell and moderate winds, it's all rideable but nothing special.
Now, looking ahead to the second week. Sunday the 16th brings a bigger pulse of 8ft from the E with an 11-second period and strong energy (1412), but the wind is a moderate cross-off. Monday the 17th pushes up to a solid 10ft from the ESE. That’s big, expert-only territory, with the wind staying cross-off. Tuesday the 18th the wind swings hard offshore from the north at 22 mph, dropping the swell to 6ft. It’s clean, but that wind is strong enough to make paddling a battle. Wednesday the 19th stays offshore but fresh, with a 7ft swell and energy ramping back up to (1102). It’s powerful and clean.
After that, the swell fades. From Thursday the 20th through the weekend of the 23rd and 24th, we're looking at small, weak surf. The 22nd and 23rd have some small S swell rolling in with a long 11-12 second period, but the wind is all over the place and the wave heights are under 3ft. The 24th is a write-off with strong onshore winds.
So, the standout sessions are clear: Sunday morning the 9th for that glassy, clean groundswell, and Tuesday morning the 11th for the big, clean, offshore-peeling lines. Get out there before the crowds (which can be 'sometimes' busy here) and you'll be smiling.
Rusty.
Short Range ForecastModerate rain (total 10mm), heaviest on Tue night. Warm (max 28°C on Sun morning, min 22°C on Mon night). Winds increasing (calm on Sun morning, fresh winds from the NE by Mon afternoon). | Days 4-6 Weather SummaryHeavy rain (total 73mm), heaviest during Fri night. Warm (max 28°C on Fri morning, min 24°C on Thu night). Wind will be generally light. | ||||||||||||||||||||
Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | |||||||||||||||
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 13 | ESE 13 | ESE 12 | E 12 | E 11 | ENE 10 | ENE 10 | E 12 | E 11 | E 10 | E 9 | E 9 | ENE 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 9 | E 9 | ESE 11 |
Wave Graph | |||||||||||||||||||||
998 | 903 | 794 | 1207 | 1095 | 1267 | 768 | 1066 | 545 | 273 | 164 | 159 | 451 | 367 | 501 | 544 | 612 | 612 | 501 | 492 | 1189 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | cross | off | cross-off | cross-off | off | off | cross-on | cross-on | cross-off | cross-off | cross | cross-off | cross-off | off | cross-off | cross-off | cross-on | cross-off | cross | cross-off |
High Tide | 4:10PM1.23m | 00:23AM1.32m | 4:33PM1.30m | 1:48AM1.37m | 4:57PM1.35m | 2:54AM1.44m | 5:21PM1.37m | 3:50AM1.49m | 5:43PM1.38m | 4:40AM1.50m | 6:04PM1.38m | 5:27AM1.47m | 6:24PM1.39m | ||||||||
Low Tide | 7:43PM1.16m | 8:40AM0.12m | 8:57PM1.09m | 9:31AM0.04m | 9:44PM0.99m | 10:15AM0.00m | 10:23PM0.88m | 10:54AM0.03m | 11:01PM0.75m | 11:29AM0.11m | 11:38PM0.63m | 12:00PM0.24m | 00:15AM0.53m | ||||||||
4:52 | — | — | 4:52 | — | — | 4:54 | — | — | 4:54 | — | — | 4:56 | — | — | 4:56 | — | — | 4:56 | — | — | |
— | 6:35 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:29 | — | — | 6:28 | — | |
mm | — | — | — | — | — | — | — | 2 | 8 | 1 | — | 19 | 15 | 3 | 2 | 1 | 3 | 29 | 6 | 8 | 6 |
Temp °C | 28 | 28 | 25 | 26 | 26 | 24 | 26 | 27 | 24 | 27 | 26 | 25 | 26 | 27 | 25 | 28 | 28 | 26 | 28 | 27 | 26 |
Feels °C | 30 | 29 | 27 | 25 | 24 | 23 | 27 | 26 | 24 | 27 | 26 | 28 | 29 | 29 | 28 | 30 | 30 | 29 | 31 | 29 | 29 |
Swell 1 Height (m) Direction Period (s) | ESE 13 | ESE 13 | ESE 12 | E 12 | SSW 11 | E 10 | ENE 10 | E 12 | E 11 | E 10 | E 9 | E 9 | ENE 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 9 | E 9 | ESE 11 |
998 | 903 | 794 | 1207 | 95 | 843 | 768 | 1066 | 545 | 273 | 164 | 159 | 451 | 367 | 501 | 544 | 612 | 612 | 501 | 492 | 1189 | |
Swell 2 Height (m) Direction Period (s) | S 10 | S 10 | S 10 | S 11 | SW 11 | S 10 | S 10 | S 11 | S 10 | S 10 | S 10 | S 10 | S 10 | SSW 10 | SSW 9 | SSW 9 | SSW 9 | SSE 11 | SSE 10 | SE 10 | S 12 |
133 | 141 | 104 | 93 | 103 | 78 | 80 | 83 | 74 | 75 | 80 | 77 | 51 | 33 | 29 | 29 | 27 | 121 | 173 | 270 | 72 | |
Swell 3 Height (m) Direction Period (s) | — | SW 12 | SW 12 | SW 12 | SSE 10 | — | SW 11 | SSW 10 | SSW 10 | SE 13 | SSE 12 | E 11 | SSE 11 | SE 11 | SE 12 | S 12 | S 12 | SE 20 | S 11 | S 11 | SE 18 |
— | 90 | 23 | 23 | 11 | — | 59 | 83 | 78 | 6 | 14 | 22 | 13 | 5 | 5 | 27 | 25 | 15 | 10 | 22 | 12 | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | E 11 | ENE 10 | NE 9 | — | S 4 | SSE 3 | ENE 3 | ENE 4 | NNE 5 | — | — | — | — | — | — | — | — |
— | — | — | — | 1095 | 1267 | 607 | — | 6 | 4 | 3 | 17 | 72 | — | — | — | — | — | — | — | — | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 0 | 57 | 0 | 51 | 51 | 51 | 0 | 23 | 17 | 68 | 51 | 12 | 0 | 51 | 0 | 56 | 51 | 9 | 0 | 51 | 51 |
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.











