
Surf Forecasts:
Onjuku surf forecast from 2 Aug 2026:
- Best quality surf: Tuesday 4 Aug, 3PM (local time) - 11ft (3.5m), 16s period, SE swell with cross-offshore winds.
- Most powerful swell: Wednesday 5 Aug, 12PM (local time) - 13ft (4.0m), 16s period, SE swell with 8,971 kJ wave energy.
- Next surfable swell (1★+): Tuesday 4 Aug, 3PM (local time) - 11ft (3.5m), 16s period with SE 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 (Aug 04) at 3PM. The primary swell is predicted to be 3.5m and 16s period with a secondary swell of 0.3m and 13s. Another secondary swell of 2.1m 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 4.0m 16s and forecast to arrive on Wednesday (Aug 05) at 12PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.3m 6s period and expected on Monday (Aug 03) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Tue 4th Aug) | 11ft (3.5m) 16s |
| Best Surf | 3PM (Tue 4th Aug) | 11ft (3.5m) 16s |
| Most Powerful | 12PM (Wed 5th Aug) | 13ft (4.0m) 16s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here. Let's have a look at what's on the menu for the next couple of weeks.
We're looking at Onjuku, and there's a bit of a story to tell. The forecast kicks off with a solid pulse of swell, but it's going to be a wild ride. For the first few days, the waves are going to be pretty heavy, and honestly, this is not a spot for the faint of heart when it gets big. The wind is a persistent cross-off from the North-Northeast, which will keep things clean, but the swell is just too meaty for a comfortable paddle.
Things start really cooking on Monday, August 3rd. The morning brings in a 6 ft swell from the SE with a very long period of 16 seconds, and the combined energy is already a solid 2033. That's a lot of power. The wind is a fresh cross-off at 19 mph, so the surface is clean, but it's a bit of a handful. By the afternoon, the swell jumps to 8 ft from the SE, with the energy kicking up to 3300. The wind picks up to 22 mph, still cross-off, but the waves are getting serious.
Tuesday, August 4th, is where it gets proper. The morning swell is 10 ft from the SE, period still 16 seconds, and the energy is a massive 4770. By Tuesday afternoon, we're looking at an 12 ft SE swell with an energy reading of 6233. The wind is still fresh and cross-off, but the waves are way too big for most. The tide is favorable, but the model is telling us this is too big for this break.
Wednesday, August 5th, is the peak of this first pulse. The swell holds at 13 ft from the SE, and the energy is a beastly 9066 in the morning and 9074 in the afternoon. The wind is still cross-off, but these waves are for experts only. The same goes for Thursday, August 6th, with the swell holding at 12 ft to 13 ft from the SSE. The wind turns a bit more cross on Thursday afternoon, with a moderate cross-shore chop, so the quality drops a little.
Friday, August 7th, sees the swell start to back off. It's still a solid 8 ft from the S in the morning, but the wind is cross, creating a moderate chop. The energy is still high at 5136. The afternoon drops to 8 ft, and the wind turns east, but the cross-shore chop remains.
The weekend of August 8th and 9th is a bit of a letdown. The swell drops to 5 ft to 6 ft from the SSW. The wind is a moderate cross-off, so it's clean, but the energy is still moderate (around 2410 to 2528). It's not terrible, but it's not the standout.
Now, the real standout window is Monday, August 10th. The morning starts with a smaller 4 ft SSW swell, but the wind goes offshore from the North-Northeast. That's a classic setup for Onjuku, and the surface will be glassy. The afternoon is where it gets interesting again. The swell jumps to 10 ft from the E with a period of 13 seconds, and the energy is back up to 6828. The wind is still cross-off and fresh, so it's clean, but that's a lot of water moving.
Tuesday, August 11th, is the best of the bunch. The morning brings a solid 12 ft ENE swell with a period of 12 seconds. The energy is huge at 6323. The wind is a moderate cross-off from the North-Northeast, so the waves will be clean and powerful. The model is saying the wind and tide are favorable, but the swell is too big for this break. For a strong intermediate or expert, this is going to be a heavy session. The afternoon drops to 8 ft, still clean, but the energy is a lot lower.
After that, things settle down. Wednesday, August 12th, to Thursday, August 13th, the swell is 5 ft to 8 ft from the ENE, with the wind staying cross-off. The energy is moderate, but it's not the same quality. By the end of the week, the swell is weak and the wind is getting strong. Friday, August 14th, is a mess with a strong offshore wind, but the period is short and the energy is low. The final weekend, August 15th to 18th, is a write-off with poor surf conditions.
So, for the best on offer, I'm looking at Monday, August 10th, for the morning glass-off. That 4 ft offshore session will be clean and fun. But the real standout is Tuesday, August 11th, in the morning. That 12 ft ENE swell, clean and powerful, is about as good as it gets here, but only if you're ready for a serious challenge. The sets will be long and the energy is intense. If you're not an expert, stay on the beach for that one.
Alright, that's the story. The second week fades out to nothing, so make the most of the first week.
Rusty.
Short Range ForecastMostly dry. Warm (max 26°C on Wed afternoon, min 23°C on Sun night). Mainly fresh winds. | Days 5-7 Weather SummaryHeavy rain (total 23mm), heaviest during Fri afternoon. Warm (max 28°C on Fri morning, min 24°C on Wed night). Wind will be generally light. | ||||||||||||||||||
Monday 3 | Tuesday 4 | Wednesday 5 | Thursday 6 | Friday 7 | Saturday 8 | ||||||||||||||
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) | SE 16 | SE 16 | SE 17 | SE 16 | SE 16 | SE 16 | SE 16 | SE 16 | SE 16 | SSE 16 | SSE 16 | SSE 16 | SSE 16 | S 16 | S 15 | S 14 | SSW 14 | SSW 15 | SSW 16 |
Wave Graph | |||||||||||||||||||
1164 | 1901 | 2970 | 3569 | 4295 | 5748 | 8157 | 8690 | 8604 | 7426 | 6999 | 7971 | 5979 | 3439 | 2525 | 1666 | 1143 | 1045 | 1602 | |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross | cross | cross | cross | cross | cross-off | cross-off | cross-off |
High Tide | 6:43AM1.30m | 7:27PM1.38m | 7:32AM1.21m | 7:51PM1.38m | 8:31AM1.11m | 8:17PM1.37m | 9:58AM1.02m | 8:49PM1.35m | 12:56PM1.00m | 9:31PM1.33m | 10:43PM1.31m | ||||||||
Low Tide | 00:59AM0.61m | 1:00PM0.40m | 1:40AM0.55m | 1:27PM0.54m | 2:28AM0.50m | 1:55PM0.69m | 3:27AM0.45m | 2:20PM0.85m | 4:43AM0.41m | 2:29PM1.00m | 6:13AM0.33m | ||||||||
— | 4:48 | — | — | 4:48 | — | — | 4:48 | — | — | 4:50 | — | — | 4:50 | — | — | 4:52 | — | — | |
6:40 | — | 6:39 | — | — | 6:38 | — | — | 6:38 | — | — | 6:37 | — | — | 6:37 | — | — | 6:36 | — | |
mm | — | — | — | — | — | — | — | — | — | 4 | 4 | 3 | 2 | 1 | 4 | 5 | — | — | — |
Temp °C | 24 | 25 | 25 | 23 | 25 | 24 | 23 | 25 | 26 | 25 | 27 | 27 | 26 | 28 | 27 | 26 | 28 | 27 | 25 |
Feels °C | 23 | 23 | 22 | 21 | 22 | 20 | 21 | 24 | 25 | 26 | 29 | 28 | 27 | 29 | 28 | 28 | 29 | 28 | 26 |
Swell 1 Height (m) Direction Period (s) | SE 16 | SE 16 | SE 17 | SE 16 | SE 16 | SE 16 | SE 16 | SE 16 | SE 16 | SSE 16 | SSE 16 | SSE 16 | SSE 16 | S 16 | S 15 | S 14 | ESE 9 | SE 9 | SSW 16 |
1164 | 1901 | 2970 | 3569 | 4295 | 5748 | 8157 | 8690 | 8604 | 7426 | 6999 | 7971 | 5979 | 3439 | 2525 | 1666 | 475 | 525 | 1602 | |
Swell 2 Height (m) Direction Period (s) | E 14 | E 14 | E 14 | E 14 | E 14 | E 13 | E 13 | — | — | E 17 | ESE 10 | E 16 | E 15 | ESE 9 | ESE 9 | SE 9 | SSW 14 | SSW 15 | ESE 9 |
65 | 34 | 61 | 33 | 57 | 30 | 87 | — | — | 22 | 383 | 20 | 41 | 666 | 591 | 505 | 1143 | 1045 | 395 | |
Swell 3 Height (m) Direction Period (s) | SW 6 | E 14 | — | — | — | — | — | — | — | ENE 16 | E 16 | ENE 16 | — | E 15 | E 15 | E 14 | S 10 | S 11 | ESE 12 |
5 | 98 | — | — | — | — | — | — | — | 26 | 20 | 51 | — | 39 | 39 | 37 | 188 | 181 | 222 | |
Wind waves Height (m) Direction Period (s) | NE 5 | NE 6 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | E 8 | E 10 | E 10 | ESE 10 | ESE 10 | ESE 9 | — | — | ESE 9 | — | — |
77 | 104 | 269 | 302 | 418 | 455 | 320 | 376 | 470 | 635 | 586 | 706 | 702 | 992 | — | — | 604 | — | — | |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 51 | 206 | 206 | 206 | 557 | 1521 | 557 | 617 | 51 | 82 | 51 | 117 | 964 | 68 | 78 | 117 | 68 | 68 | 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.











