Surf Forecasts:
Onjuku surf forecast from 25 Aug 2026:
- Best quality surf: Tuesday 1 Sep, 12PM (local time) - 3.5ft (1.1m), 12s period, S swell with cross-offshore winds.
- Most powerful swell: Wednesday 2 Sep, 3AM (local time) - 5ft (1.5m), 13s period, S swell with 759 kJ wave energy.
- Next surfable swell (1★+): Thursday 27 Aug, 9AM (local time) - 2.5ft (0.8m), 10s period with SSE 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 Thursday (Aug 27) at 9AM. The primary swell is predicted to be 0.8m and 10s period with a secondary swell of 0.9m and 6s. Another secondary swell of 1.3m and 5s 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 1.5m 13s and forecast to arrive on Wednesday (Sep 02) 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 1.0m 5s period and expected on Saturday (Aug 29) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Thu 27th Aug) | 2.5ft (0.8m) 10s |
| Best Surf | 12PM (Tue 1st Sep) | 3.5ft (1.1m) 12s |
| Most Powerful | 3AM (Wed 2nd Sep) | 5ft (1.5m) 13s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
G'day, Rusty here. Look, I gotta be straight with you—the next 16 days at Onjuku are a mixed bag, and we're starting off with a bit of a dud before things get interesting. The first few days are a write-off, but there's a glimmer of light later on.
We kick off on Wednesday, August 26th, and it's a shocker. The swell is a tiny 3 ft from the SSE with a short period of 10 seconds, but it's blown out by a cross-onshore wind. The energy is moderate (353), but the surf is just poor. Thursday the 27th is a little better. The swell drops to 3 ft from the SSE, but the wind swings to a light cross-offshore in the morning, making things clean. The combined energy is moderate (330). The afternoon cleans up even more with a gentle offshore breeze from the NNE and a nice 2 ft swell from the east with a 13-second period—that's a proper groundswell. The energy is solid (290). This is about as good as it gets for the first week, but it's still small, ankle-to-knee high stuff.
The 28th and 29th are a write-off with poor surf and messy winds. Then Sunday, August 30th, has a glassy morning with a tiny 2 ft easterly swell (11 sec period) and weak energy (93). It's surfable but very ordinary. The rest of the week is much of the same, with small, clean conditions but no real power.
Now, hold onto your board. The standout is on Tuesday, September 8th. The swell is huge, with a 13 ft to 15 ft SSE swell rolling in. The combined energy is massive (4536-5031), and it's a long-period groundswell at 12 seconds. The wind is moderate cross-shore to cross-offshore, keeping things somewhat clean. Here's the catch: this is way too big for beginners and only for experts. It's a long-period swell, so it'll be walling up a bit at the beach break, but for the experienced crew, it's going to be a proper session. The water temperature is about average for the time of year, but with that much energy, you won't be thinking about that.
The 9th and 10th of September see the swell drop back down, but it's still sizeable at 7 ft, though the wind is strong and cross-offshore, making it a bit of a battle. The whole period is a slow burn, but that one day on the 8th is the only real standout. If you're not an expert, the best bet is the small, clean conditions on Thursday the 27th.
So, for the first week, it's a lot of waiting. The second week brings the monster, but it's for the brave only. Stay tuned, forecasts can change.
Rusty.
Short Range ForecastModerate rain (total 17mm), heaviest on Thu morning. Warm (max 30°C on Wed morning, min 24°C on Thu afternoon). Winds decreasing (fresh winds from the SW on Wed night, light winds from the NE by Thu afternoon). | Days 5-7 Weather SummaryLight rain (total 3mm), mostly falling on Mon morning. Warm (max 26°C on Fri night, min 23°C on Sat night). Wind will be generally light. | ||||||||||||||||||
Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | Monday 31 | ||||||||||||||
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) | S 12 | SSE 10 | SSE 9 | SSE 9 | SSE 10 | E 13 | E 13 | E 12 | SSW 8 | E 12 | E 12 | E 11 | E 11 | E 11 | E 11 | E 11 | E 11 | E 11 | S 12 |
Wave Graph | |||||||||||||||||||
287 | 159 | 146 | 113 | 120 | 173 | 163 | 148 | 125 | 99 | 96 | 60 | 58 | 57 | 63 | 58 | 58 | 58 | 105 | |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-on | cross-on | cross-off | off | on | cross | cross-on | off | cross-off | cross-off | off | glassy | cross | cross-off | cross-off | off | off |
High Tide | 2:31AM1.30m | 4:41PM1.29m | 3:17AM1.37m | 4:57PM1.33m | 3:58AM1.42m | 5:14PM1.37m | 4:38AM1.44m | 5:32PM1.40m | 5:17AM1.43m | 5:51PM1.42m | 5:58AM1.39m | 6:10PM1.43m | |||||||
Low Tide | 9:22PM0.95m | 9:42AM0.22m | 9:51PM0.85m | 10:12AM0.19m | 10:21PM0.74m | 10:41AM0.20m | 10:51PM0.63m | 11:09AM0.24m | 11:22PM0.53m | 11:35AM0.32m | 11:54PM0.43m | 12:02PM0.43m | 00:30AM0.36m | ||||||
— | 5:05 | — | — | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — | 5:07 | — | — | 5:09 | — | — | |
6:15 | — | 6:14 | — | — | 6:13 | — | — | 6:12 | — | — | 6:09 | — | — | 6:08 | — | — | 6:07 | — | |
mm | — | — | — | — | 11 | 2 | 2 | 2 | — | — | — | — | — | — | — | 1 | 2 | — | — |
Temp °C | 27 | 30 | 29 | 27 | 27 | 25 | 26 | 28 | 28 | 26 | 26 | 26 | 25 | 26 | 25 | 24 | 23 | 24 | 24 |
Feels °C | 28 | 32 | 30 | 28 | 32 | 27 | 29 | 30 | 30 | 31 | 26 | 26 | 27 | 30 | 28 | 24 | 24 | 25 | 27 |
Swell 1 Height (m) Direction Period (s) | SSE 10 | SSE 10 | SSE 9 | SSE 9 | SSW 6 | SSW 6 | S 9 | SSW 6 | E 12 | SSW 6 | E 12 | E 11 | E 5 | E 11 | E 11 | E 11 | E 11 | E 11 | S 12 |
237 | 159 | 146 | 113 | 48 | 37 | 134 | 55 | 103 | 40 | 96 | 60 | 43 | 57 | 63 | 58 | 58 | 58 | 105 | |
Swell 2 Height (m) Direction Period (s) | S 12 | SSW 5 | ESE 12 | E 12 | SSE 10 | E 13 | E 13 | E 12 | SE 9 | E 12 | S 8 | SSW 8 | E 11 | E 5 | ENE 5 | SSW 7 | SSW 7 | S 10 | ENE 7 |
287 | 24 | 113 | 70 | 120 | 173 | 163 | 148 | 22 | 99 | 30 | 20 | 58 | 11 | 10 | 18 | 15 | 52 | 34 | |
Swell 3 Height (m) Direction Period (s) | ESE 13 | S 12 | S 12 | SSW 11 | E 11 | SSE 10 | SE 10 | S 9 | SE 15 | SE 9 | SE 11 | SE 11 | SSW 8 | SE 10 | SSW 8 | SE 10 | SE 9 | NE 7 | S 10 |
176 | 101 | 101 | 47 | 59 | 80 | 26 | 36 | 8 | 23 | 30 | 30 | 20 | 25 | 19 | 26 | 22 | 19 | 65 | |
Wind waves Height (m) Direction Period (s) | SW 5 | SW 5 | SSW 5 | SSW 5 | SW 5 | NE 4 | SSW 6 | SW 6 | SSW 8 | — | NE 3 | ENE 5 | — | — | NNE 5 | ENE 5 | NE 4 | ENE 5 | — |
36 | 69 | 52 | 55 | 103 | 7 | 28 | 112 | 125 | — | 2 | 53 | — | — | 2 | 18 | 16 | 15 | — | |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 18 | 2 | 88 | 18 | 0 | 0 | 9 | 2 | 2 | 0 | 56 | 56 | 0 | 0 | 22 | 557 | 22 | 0 | 0 |
Best forecast wave conditions in Chiba | |||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||
Header Global | |||||||||||||||||||
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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.











