
Surf Forecasts:
Onjuku surf forecast from 6 Aug 2026:
- Best quality surf: Sunday 9 Aug, 12AM (local time) - 5.5ft (1.7m), 14s period, ESE swell with glassy winds.
- Most powerful swell: Tuesday 11 Aug, 6AM (local time) - 10ft (3.0m), 10s period, NE swell with 2,000 kJ wave energy.
- Next surfable swell (1★+): Sunday 9 Aug, 12AM (local time) - 5.5ft (1.7m), 14s 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 12AM. The primary swell is predicted to be 1.7m and 14s period with a secondary swell of 1.0m and 11s. 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 10s and forecast to arrive on Tuesday (Aug 11) at 6AM. Winds are predicted to be offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.9m 4s period and expected on Monday (Aug 10) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12AM (Sun 9th Aug) | 5.5ft (1.7m) 14s |
| Best Surf | 12AM (Sun 9th Aug) | 5.5ft (1.7m) 14s |
| Most Powerful | 6AM (Tue 11th Aug) | 10ft (3.0m) 10s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, this is Rusty here, checking in on the local surf scene for the next couple of weeks.
Alright, so we’ve got a bit of a mixed bag on the way. The first decent surf rolls in on Thursday morning, the 6th, and it’s a solid one if you’ve got the skills. The sea is pumping with a strong 7ft SSE swell, and the combined energy is a hefty 1955, so there’s some serious power in the water. The water’s sitting at 78°, which is pretty much what you’d expect for this time of year. The wind is a clean cross-offshore from the ENE, and the period is a meaty 13 seconds, so the waves are going to have some real shape to them. This is an exposed spot, so it’s getting all that energy. The catch is, this is about as good as it gets for the whole run, but with that size, it’s strictly for the experienced crew. Beginners, stay on the beach for this one. It’s also inconsistent here, so don’t expect a wave every minute, but when they come, they’ll be worth it.
Thursday afternoon, the wind swings to a cross-on from the ESE, and the quality drops off with the chop. Don’t get excited about that session.
Friday the 7th is a write-off. We’ve got a risk of thunderstorms and a cross-on wind that’s going to make a mess of the 6ft S swell. Not worth paddling out.
Saturday the 8th drops off further. The swell is down to 4ft in the morning and the wind is light cross-on. The energy is weak at 604, so it’s a small, choppy day.
Now, Sunday the 9th looks like the real standout. The swell is 6ft from the ESE, and the wind is a light cross-offshore from the ENE. That’s the magic combo. The period is a nice 13 seconds, so the lines will be clean. The energy is strong at 1188. This is the best session for the intermediate surfer, with much cleaner, more manageable waves than Thursday. This is the one to circle on the calendar. It’s still inconsistent, so be patient, but the quality will be there.
Monday the 10th picks up a fresh 19 mph NE wind. The swell is 5ft from the E. The wind is cross-off, so it’s clean, but that wind strength is going to make it a battle. The energy is low at 759. It’s a tough paddle for not much reward.
Tuesday the 11th has a great morning window. The swell is 6ft from the ENE and the wind is a clean offshore from the N. The period is 11 seconds, and the energy is strong at 1363. This is another one for the experienced crew, as it’s a powerful wave. The afternoon is a bust with a strong breeze from the NNE.
From Wednesday the 12th onwards, the overall trend is a slow decline. The swell holds around 5ft to 6ft for a few days, but it’s mostly from the E or NE. The wind is consistently cross-offshore, which is a positive, keeping the faces clean. The energy drops into the three-digit range, and the periods settle around 8 to 11 seconds. The quality is marginal, with the best chance being a ‘very good’ call on Friday morning the 14th, with a 5ft E swell and light cross-off wind. But it’s not a patch on the first week.
The second week from the 16th onwards is the real slump. The swell drops to 3ft to 5ft, and the energy is weak, often below 400. The wind stays cross-off, keeping it clean, but the waves are just too small and weak to get excited about. The period drops to 8-10 seconds, so it’s short-period windswell. There’s no real punch. The 19th is a flat-out ‘poor’ call, and it just fades out from there.
To sum it up: Thursday morning the 6th is the big, powerful day for the experts. Sunday the 9th is the best all-rounder for the intermediate surfer, with clean, fun waves. The rest is a slow fade into small, clean but weak conditions. Get your sessions in early.
Rusty.
Short Range ForecastLight rain (total 3mm), mostly falling on Thu night. Warm (max 28°C on Thu afternoon, min 24°C on Sat night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 26°C on Sun afternoon, min 23°C on Sun night). Winds increasing (light winds from the ENE on Sun afternoon, strong winds from the NNE by Tue morning). | |||||||||||||||||||
Thu 6 | Friday 7 | Saturday 8 | Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | ||||||||||||||
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) | SSE 12 | S 13 | S 12 | S 12 | S 11 | S 11 | ESE 13 | ESE 14 | ESE 13 | ESE 13 | ESE 12 | E 12 | ENE 11 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 9 | ENE 9 | ENE 11 |
Wave Graph | ||||||||||||||||||||
1405 | 1684 | 957 | 702 | 457 | 344 | 624 | 1038 | 998 | 917 | 794 | 997 | 1363 | 1124 | 1306 | 1339 | 1205 | 708 | 627 | 1421 | |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-on | on | on | cross-on | cross-on | glassy | cross-off | cross-off | off | cross-off | cross-off | off | off | cross-off | off | cross-off | cross-off | off |
High Tide | 8:49PM1.35m | 12:56PM1.00m | 9:31PM1.33m | 10:43PM1.31m | 4:10PM1.23m | 00:23AM1.32m | 4:33PM1.30m | 1:48AM1.37m | 4:57PM1.35m | 2:54AM1.44m | 5:21PM1.37m | |||||||||
Low Tide | 4:43AM0.41m | 2:29PM1.00m | 6:13AM0.33m | 7:36AM0.23m | 7:43PM1.16m | 8:40AM0.12m | 8:57PM1.09m | 9:31AM0.04m | 9:44PM0.99m | 10:15AM0.00m | 10:23PM0.88m | |||||||||
— | — | 4:50 | — | — | 4:52 | — | — | 4:52 | — | — | 4:52 | — | — | 4:54 | — | — | 4:54 | — | — | |
6:37 | — | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | |
mm | — | 1 | 2 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 11 |
Temp °C | 28 | 26 | 28 | 28 | 26 | 28 | 27 | 25 | 27 | 26 | 24 | 26 | 26 | 24 | 26 | 26 | 24 | 25 | 26 | 24 |
Feels °C | 31 | 30 | 30 | 31 | 29 | 31 | 29 | 28 | 28 | 26 | 25 | 22 | 23 | 21 | 22 | 22 | 21 | 24 | 25 | 25 |
Swell 1 Height (m) Direction Period (s) | SSE 12 | S 13 | S 12 | S 12 | S 11 | S 11 | ESE 13 | ESE 14 | ESE 13 | ESE 13 | ESE 12 | E 12 | E 11 | S 10 | S 12 | S 11 | SSW 12 | S 11 | E 13 | E 11 |
1405 | 1684 | 957 | 702 | 457 | 344 | 624 | 1038 | 998 | 917 | 794 | 997 | 969 | 53 | 69 | 66 | 79 | 66 | 90 | 1048 | |
Swell 2 Height (m) Direction Period (s) | ESE 10 | ESE 10 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | S 11 | S 11 | S 11 | S 11 | SSW 12 | SSW 11 | S 11 | SW 12 | SSW 12 | SW 12 | SW 12 | — | S 11 | SSW 11 |
305 | 346 | 272 | 288 | 288 | 236 | 284 | 240 | 146 | 146 | 183 | 126 | 83 | 23 | 15 | 72 | 73 | — | 66 | 40 | |
Swell 3 Height (m) Direction Period (s) | E 16 | E 15 | E 15 | E 15 | E 14 | E 14 | E 10 | — | — | SW 11 | SW 12 | SW 12 | WSW 12 | SSW 11 | — | — | — | — | E 14 | — |
20 | 41 | 39 | 39 | 37 | 36 | 47 | — | — | 127 | 175 | 118 | 15 | 90 | — | — | — | — | 179 | — | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | N 4 | ENE 11 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 9 | ENE 9 | ENE 11 |
— | — | — | — | — | — | — | — | — | — | — | 7 | 1363 | 1124 | 1306 | 1339 | 1205 | 708 | 627 | 1421 | |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 9 | 9 | 9 | 9 | 9 | 9 | 9 | 0 | 0 | 56 | 0 | 56 | 51 | 110 | 206 | 536 | 51 | 51 | 56 | 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.











