Surf Forecasts:
Onjuku surf forecast from 28 Jul 2026:
- Best quality surf: Tuesday 4 Aug, 3AM (local time) - 11ft (3.5m), 18s period, SE swell with cross-offshore winds.
- Most powerful swell: Tuesday 4 Aug, 9PM (local time) - 15ft (4.5m), 18s period, SE swell with 12,346 kJ wave energy.
- Next surfable swell (1★+): Wednesday 29 Jul, 9PM (local time) - 3ft (0.9m), 7s period with SSW 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 (Jul 29) at 9PM. The primary swell is predicted to be 0.9m and 7s period with a secondary swell of 0.4m and 9s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 4.5m 18s and forecast to arrive on Tuesday (Aug 04) at 9PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 3s period and expected on Thursday (Jul 30) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Wed 29th Jul) | 3ft (0.9m) 7s |
| Best Surf | 3AM (Tue 4th Aug) | 11ft (3.5m) 18s |
| Most Powerful | 9PM (Tue 4th Aug) | 15ft (4.5m) 18s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Righteo, Rusty here. Let’s have a look at what’s cookin’ for the next couple of weeks.
First up, we’ve got a bit of a quiet spell to start. The surf is pretty ordinary through the end of July and into the first few days of August. We’re looking at small, weak swells with a lot of onshore or cross-onshore wind, making for choppy, messy conditions. The combined wave energy is pretty low, mostly under 100 (117) or just a bit over, so don’t get your hopes up for anything worth paddling out for. The water temp is sitting around 81°, which is about normal for this time of year.
Now, things get real interesting from the 3rd of August onwards. We’ve got a serious pulse of swell pushing in. Monday the 3rd sees a jump in size, with a 8ft to 10ft SE groundswell rolling in with a very long period of 17 seconds. The energy jumps right up to 3326, and then 4527. The wind is light and cross-shore, so it’ll be a bit lumpy, but there’s legit power. This is big, proper groundswell, and with that period, it’ll be offering up some very long, clean lines. This is not for beginners, though – over 8ft, that’s expert territory.
The absolute standout is Tuesday the 4th and Wednesday the 5th of August. We’re talking a massive SE swell, 12ft to 18ft, with a period of 17 to 18 seconds. The energy is huge, pushing 7940, 9588, and even 17642. The real kicker is the wind: it’s a clean cross-offshore breeze from the NE, light to moderate. This is the kind of setup that turns a spot like Onjuku into a dream. The swell is very big, so only for the experienced crew, but if you’ve got the skills, this is the session to aim for. The combination of size, long period, and clean wind is about as good as it gets.
After that, the swell drops back a bit, but there’s still some decent, albeit smaller, action through the 7th and 8th, with some onshore winds and storm risk creeping in. The surf is still there, but it’s not the same quality.
So, to sum it up: the first week is a dud, but the 4th and 5th of August are the undisputed standouts. Huge, long-period SE groundswell with glassy offshore winds. It’s a guaranteed all-time session if you can handle the size.
Rusty.
Short Range ForecastLight rain (total 4mm), mostly falling on Tue night. Warm (max 29°C on Wed morning, min 25°C on Tue night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 28°C on Fri afternoon, min 25°C on Fri night). Wind will be generally light. | |||||||||||||||||||
Tue 28 | Wednesday 29 | Thursday 30 | Friday 31 | Saturday 1 | Sunday 2 | Monday 3 | ||||||||||||||
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) | ENE 8 | ENE 8 | SW 7 | SW 7 | SSW 7 | SSW 7 | S 7 | SE 9 | SE 9 | S 6 | SE 10 | SE 11 | SE 14 | SE 14 | SE 14 | SE 15 | SE 16 | SE 17 | SE 17 | SE 18 |
Wave Graph  | ||||||||||||||||||||
 kJ | 58 | 45 | 258 | 200 | 59 | 43 | 40 | 22 | 31 | 27 | 23 | 29 | 47 | 102 | 373 | 714 | 1456 | 3235 | 4466 | 6083 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross-on | cross-on | cross-on | cross-off | cross-off | on | glassy | cross-off | cross | cross-off | cross-off | cross-on | cross-on | cross | cross-on | cross-on | cross | cross | cross-off |
High Tide | 5:21PM1.27m | 3:19AM1.38m | 5:42PM1.30m | 4:01AM1.42m | 6:03PM1.32m | 4:41AM1.43m | 6:23PM1.34m | 5:20AM1.41m | 6:44PM1.36m | 6:00AM1.37m | 7:05PM1.38m | 6:43AM1.30m | 7:27PM1.38m | |||||||
Low Tide | 10:04PM0.97m | 10:37AM0.13m | 10:38PM0.90m | 11:08AM0.12m | 11:11PM0.83m | 11:38AM0.14m | 11:45PM0.75m | 12:06PM0.20m | 00:21AM0.68m | 12:33PM0.28m | 00:59AM0.61m | 1:00PM0.40m | 1:40AM0.55m | |||||||
 |  |  | |  | | |  |  | |  | | | | | | | | | | |
 | — | — | 4:43 | — | — | 4:45 | — | — | 4:46 | — | — | 4:46 | — | — | 4:47 | — | — | 4:48 | — | — |
 | 6:45 | — | — | 6:45 | — | — | 6:44 | — | — | 6:43 | — | — | 6:42 | — | — | 6:40 | — | — | 6:39 | — |
mm | — | 3 | — | — | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 27 | 27 | 29 | 29 | 27 | 29 | 28 | 27 | 28 | 28 | 26 | 27 | 27 | 26 | 28 | 28 | 26 | 27 | 27 | 25 |
Feels °C | 29 | 29 | 32 | 32 | 32 | 33 | 30 | 31 | 30 | 31 | 29 | 30 | 30 | 30 | 31 | 31 | 30 | 30 | 29 | 27 |
Swell 1 Height (m) Direction Period (s) | ENE 8 | ENE 8 | SSW 7 | SSW 7 | SSW 7 | SSW 7 | S 7 | S 6 | S 6 | S 6 | S 7 | S 6 | ESE 10 | ESE 10 | SE 14 | SE 15 | SE 16 | SE 17 | SE 17 | SE 18 |
| kJ | 58 | 45 | 105 | 89 | 59 | 43 | 40 | 20 | 31 | 27 | 21 | 13 | 37 | 67 | 373 | 714 | 1456 | 3235 | 4466 | 6083 |
Swell 2 Height (m) Direction Period (s) | SE 10 | SE 10 | SE 10 | SE 10 | SE 10 | ESE 9 | SE 9 | SE 9 | SE 9 | ENE 8 | NE 7 | NE 7 | NE 7 | SE 4 | SE 4 | NE 7 | E 14 | E 14 | E 14 | E 14 |
| kJ | 35 | 35 | 44 | 33 | 23 | 32 | 31 | 22 | 30 | 23 | 19 | 19 | 14 | 13 | 9 | 8 | 65 | 61 | 61 | 132 |
Swell 3 Height (m) Direction Period (s) | SSW 8 | SE 13 | ENE 6 | NE 9 | E 9 | ENE 4 | ENE 8 | ENE 8 | NE 8 | SE 9 | SE 10 | SE 11 | SE 14 | SE 14 | NE 7 | E 15 | NE 7 | — | — | — |
| kJ | 24 | 27 | 8 | 12 | 14 | 3 | 13 | 13 | 16 | 13 | 23 | 29 | 47 | 102 | 9 | 38 | 13 | — | — | — |
Wind waves Height (m) Direction Period (s) | — | SSW 5 | SW 7 | SW 7 | NE 7 | — | — | — | — | — | — | — | ESE 4 | — | — | ESE 4 | ENE 7 | ENE 7 | — | — |
| kJ | — | 34 | 258 | 200 | 8 | — | — | — | — | — | — | — | 7 | — | — | 7 | 35 | 30 | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 9 | 9 | 9 | 9 | 0 | 0 | 9 | 0 | 0 | 598 | 0 | 0 | 9 | 9 | 9 | 9 | 9 | 9 | 51 | 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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