Surf Forecasts:
Onjuku surf forecast from 22 Aug 2026:
- Best quality surf: Monday 24 Aug, 6AM (local time) - 2.5ft (0.8m), 18s period, SSE swell with glassy winds.
- Most powerful swell: Tuesday 25 Aug, 12AM (local time) - 7ft (2.1m), 14s period, SSE swell with 1,800 kJ wave energy.
- Next surfable swell (1★+): Sunday 23 Aug, 9AM (local time) - 2.5ft (0.7m), 9s period with E 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 23) at 9AM. The primary swell is predicted to be 0.7m and 9s period with a secondary swell of 0.3m and 9s. 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 2.1m 14s and forecast to arrive on Tuesday (Aug 25) at 12AM. 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 Sunday (Aug 30) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Sun 23rd Aug) | 2.5ft (0.7m) 9s |
| Best Surf | 6AM (Mon 24th Aug) | 2.5ft (0.8m) 18s |
| Most Powerful | 12AM (Tue 25th Aug) | 7ft (2.1m) 14s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Righto, Rusty here. Let’s have a look at what’s coming up for Onjuku.
We’re in for a bit of a wait, honestly. The first few days are pretty ordinary. Sunday the 23rd might get you wet, but the waves are only 2ft from the east with a bit of a cross-off breeze and a period of 9 seconds. The combined energy is weak (102). It’s surfable, but you wouldn’t drive out of your way for it. The water is sitting at 81°, which is about average for the time of year.
Now, Monday morning the 24th is where it gets interesting. This is the standout of the whole outlook. The wind goes glassy, dead calm, and the swell jumps to 3ft from the SSE with a long period of 18 seconds – that’s proper groundswell energy. The combined energy is strong at 941. Onjuku is an exposed beach break, so a long period like that can make it a bit straight, but with glassy conditions and that quality, it’s going to be clean and have some push. The best session of the whole run.
Monday afternoon the 24th gets messy quick. The wind swings cross-on from the SSW at 12 mph, and the swell jumps to 6ft, but it’s choppy and poor. The rest of that week and into the start of September is a write-off: strong winds, onshore, and lumpy. There’s a bit of a gap there from Tuesday the 25th all the way through to the end of the month with no real quality. A few mornings around the 31st of August and 1st of September offer some hope with clean conditions and 4ft to 4ft from the ESE, but it’s marginal. The 1st of September Tuesday afternoon sees a proper offshore wind from the NNE at 12 mph, and the combined energy is 841 – that’s a solid moderate wave energy. That could be a fun session, but it’s not a standout like Monday the 24th.
After that, the outlook fades again with more onshore and messy conditions through the first week of September. The swell tries to pick up a bit on the 7th of September, but it’s short period (8 seconds) and cross-on, so it’s not really worth the paddle.
So, if you’ve got a window, make it Monday morning the 24th of August. Glassy, 3ft SSE groundswell, and that long period will give you some proper lines. The rest of the run is a bit of a dud for quality surf.
Rusty.
Short Range ForecastMostly dry. Warm (max 28°C on Mon morning, min 25°C on Sun morning). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 8mm), mostly falling on Fri morning. Warm (max 29°C on Wed morning, min 24°C on Fri morning). Winds decreasing (fresh winds from the SW on Thu night, light winds from the NE by Fri night). | ||||||||||||||||||||
Sunday 23 | Monday 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | |||||||||||||||
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) | E 9 | SSE 12 | SSE 12 | SSE 18 | SSE 16 | SSE 14 | SSE 13 | SSE 13 | S 13 | S 12 | S 13 | SSW 12 | S 9 | E 13 | SSW 9 | E 12 | E 12 | E 12 | E 12 | E 11 | E 11 |
Wave Graph  | |||||||||||||||||||||
 kJ | 83 | 104 | 196 | 459 | 1634 | 1800 | 968 | 1327 | 972 | 344 | 334 | 195 | 251 | 173 | 206 | 146 | 139 | 137 | 98 | 87 | 84 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | glassy | glassy | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross | cross-off | cross-off | cross | cross | cross |
High Tide | 4:31PM1.15m | 11:58PM1.18m | 4:19PM1.20m | 1:32AM1.23m | 4:27PM1.25m | 2:31AM1.30m | 4:41PM1.29m | 3:17AM1.37m | 4:57PM1.33m | 3:58AM1.42m | 5:14PM1.37m | 4:38AM1.44m | 5:32PM1.40m | ||||||||
Low Tide | 7:50PM1.12m | 8:27AM0.35m | 8:48PM1.04m | 9:08AM0.28m | 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 | ||||||||
 | |  | |  |  | | | | | | | |  |  |  | | | | | | |
 | 5:03 | — | — | 5:03 | — | — | 5:05 | — | — | 5:05 | — | — | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — |
 | — | 6:17 | — | — | 6:16 | — | — | 6:15 | — | — | 6:14 | — | — | 6:13 | — | — | 6:12 | — | — | 6:09 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 | 2 | 4 | 1 | — | — | — | — |
Temp °C | 27 | 27 | 25 | 28 | 28 | 26 | 28 | 28 | 27 | 29 | 29 | 27 | 29 | 29 | 27 | 26 | 24 | 24 | 26 | 26 | 25 |
Feels °C | 30 | 30 | 30 | 31 | 29 | 28 | 29 | 28 | 28 | 30 | 30 | 28 | 30 | 29 | 28 | 27 | 23 | 24 | 26 | 26 | 26 |
Swell 1 Height (m) Direction Period (s) | E 9 | E 9 | SSE 12 | SSE 12 | SSE 16 | SSE 14 | SSE 13 | SSE 13 | S 13 | S 12 | S 13 | SSW 12 | S 9 | S 8 | S 9 | S 8 | S 8 | S 8 | S 9 | S 9 | E 6 |
| kJ | 83 | 80 | 196 | 226 | 1634 | 1800 | 968 | 1327 | 972 | 344 | 334 | 195 | 251 | 136 | 123 | 91 | 84 | 65 | 78 | 57 | 48 |
Swell 2 Height (m) Direction Period (s) | SSW 9 | SSE 12 | E 9 | SSE 18 | ESE 12 | ESE 11 | S 15 | ESE 13 | ESE 13 | SSE 11 | SSE 9 | SSE 9 | SSW 12 | E 13 | E 13 | E 12 | E 12 | E 12 | E 12 | E 11 | E 11 |
| kJ | 15 | 104 | 56 | 459 | 109 | 95 | 648 | 181 | 176 | 149 | 124 | 82 | 78 | 173 | 163 | 146 | 139 | 137 | 98 | 87 | 84 |
Swell 3 Height (m) Direction Period (s) | SSE 4 | ESE 12 | ESE 12 | SSE 15 | E 8 | ESE 15 | ESE 14 | — | E 19 | ESE 12 | ESE 12 | E 12 | E 11 | SSE 10 | SSE 10 | SE 10 | SE 9 | SE 10 | SE 11 | SSE 11 | S 8 |
| kJ | 4 | 57 | 50 | 256 | 33 | 42 | 201 | — | 7 | 117 | 113 | 70 | 58 | 38 | 38 | 24 | 23 | 23 | 30 | 47 | 37 |
Wind waves Height (m) Direction Period (s) | NNE 3 | NE 3 | — | — | — | SW 8 | SSW 4 | SSW 4 | SSW 4 | SSW 4 | SSW 4 | S 5 | SW 5 | SW 5 | SSW 9 | — | NE 2 | NE 4 | E 5 | E 6 | — |
| kJ | 1 | 3 | — | — | — | 57 | 14 | 18 | 8 | 16 | 25 | 66 | 60 | 31 | 206 | — | 1 | 6 | 24 | 55 | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 0 | 0 | 0 | 0 | 17 | 101 | 88 | 583 | 88 | 88 | 557 | 101 | 18 | 101 | 143 | 18 | 51 | 0 | 51 | 9 | 9 |
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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