Surf Forecasts:
Onjuku surf forecast from 14 Sep 2026:
- Best quality surf: Saturday 19 Sep, 12PM (local time) - 10ft (3.0m), 13s period, SE swell with offshore winds.
- Most powerful swell: Saturday 19 Sep, 12PM (local time) - 10ft (3.0m), 13s period, SE swell with 3,057 kJ wave energy.
- Next surfable swell (1★+): Wednesday 16 Sep, 12AM (local time) - 3.5ft (1.1m), 9s 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 Wednesday (Sep 16) at 12AM. The primary swell is predicted to be 1.1m and 9s period with a secondary swell of 0.7m and 13s. Another secondary swell of 1.1m and 6s is also forecast. 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 13s and forecast to arrive on Saturday (Sep 19) at 12PM. Winds are predicted to be 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 Wednesday (Sep 16) at 9PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12AM (Wed 16th Sep) | 3.5ft (1.1m) 9s |
| Best Surf | 12PM (Sat 19th Sep) | 10ft (3.0m) 13s |
| Most Powerful | 12PM (Sat 19th Sep) | 10ft (3.0m) 13s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
G’day, Rusty here. Look, I’ve been staring at the charts for Onjuku and the first week or so is a bit of a write-off, to be honest. You’ve got a long stretch of poor conditions with cross-onshore winds and only tiny, messy swell. The wait will be worth it, though, because a proper pulse of groundswell kicks in later on. The water temp is sitting around 78.3°, which is just about average for this time of year, nothing unusual there.
The first real flicker of life comes on Wednesday, 16th September, with a small 2.6 ft SE swell, but the wind is a messy cross-off, so it’s only a marginal hope. Thursday the 17th sees a jump in size to 6.2 ft NE, but that’s a short-period 7-second affair and a strong breeze is ruining it. Not worth paddling out.
The standout window is Saturday the 19th and Sunday the 20th. On Saturday afternoon, the wind drops to glassy, absolutely dead calm. You’ve got a solid 9.8 ft SE groundswell rolling in with a 12-second period. The combined wave energy is hitting 2882 (moderate to strong), packing a punch. This is expert territory only—over 8.2 ft is big, powerful stuff. The wind is offshore on Sunday morning too, with a 12 mph northing keeping it clean. That’s your best shot at a proper session: Saturday afternoon for the glass, Sunday morning for the clean offshore lines. The swell direction is SSE, which is right on the money for Onjuku’s optimum. Expect it to be a bit inconsistent, as the place is known for that, and there will be crowds around, so get in early.
After that, Monday the 21st still has some 6.2 ft S swell with moderate cross-off winds, but the energy and quality drop off. By Tuesday the 22nd, the swell pumps up again to 18 ft SSE with a 10-second period. The combined energy is 5430 (very strong). That’s massive and, frankly, too big for this break. It’ll be a washing machine and more for the tow crew or kite surfers than paddle surfing.
The last week of the month fades back into small, weak, cross-off conditions with only marginal hope for a wave. Nothing to get excited about.
Best on offer: Saturday 19th September afternoon at Onjuku—dead glassy, 9.8 ft SE groundswell, for experienced surfers only. Sunday 20th September morning is the clean runner-up with offshore winds and similar size.
Stay stoked.
Short Range ForecastHeavy rain (total 62mm), heaviest during Tue morning. Warm (max 26°C on Mon afternoon, min 20°C on Wed night). Winds increasing (calm on Tue night, strong winds from the NNE by Thu morning). | Days 5-7 Weather SummaryHeavy rain (total 64mm), heaviest during Sat afternoon. Warm (max 24°C on Sat night, min 20°C on Thu afternoon). Winds decreasing (strong winds from the NNE on Thu afternoon, calm by Sat afternoon). | |||||||||||||||||||
Mon 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | ||||||||||||||
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) | SE 9 | SSE 9 | E 14 | E 14 | SE 9 | E 13 | E 12 | NE 6 | NE 7 | ENE 8 | ENE 8 | ENE 8 | SE 16 | SE 14 | SE 13 | SE 12 | SE 12 | SE 13 | SE 12 | SE 13 |
Wave Graph  | ||||||||||||||||||||
 kJ | 147 | 264 | 195 | 261 | 193 | 215 | 148 | 175 | 394 | 546 | 634 | 705 | 1317 | 2630 | 2574 | 2597 | 2078 | 2483 | 2195 | 2140 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-on | on | glassy | cross-off | cross-off | cross-off | cross-off | cross-off | off | off | cross-off | off | off | glassy | glassy | off | cross-off | cross-off |
High Tide | 5:44PM1.44m | 6:45AM1.29m | 6:03PM1.43m | 7:26AM1.19m | 6:22PM1.41m | 8:14AM1.09m | 6:42PM1.37m | 9:27AM0.99m | 7:03PM1.31m | 7:24PM1.24m | 7:46PM1.15m | |||||||||
Low Tide | 00:19AM0.26m | 12:11PM0.69m | 00:53AM0.27m | 12:28PM0.79m | 1:31AM0.32m | 12:40PM0.87m | 2:15AM0.40m | 12:34PM0.94m | 3:18AM0.48m | 5:00AM0.52m | ||||||||||
 |  |  | |  |  |  |  |  |  |  | | | | | |  | | | | |
 | — | — | 5:20 | — | — | 5:20 | — | — | 5:22 | — | — | 5:22 | — | — | 5:22 | — | — | 5:24 | — | — |
 | 5:47 | — | — | 5:46 | — | — | 5:45 | — | — | 5:44 | — | — | 5:42 | — | — | 5:40 | — | — | 5:38 | — |
mm | — | 3 | 11 | 4 | 14 | 7 | 13 | 9 | 1 | — | — | — | — | 1 | 18 | 25 | 19 | 1 | — | — |
Temp °C | 26 | 26 | 25 | 24 | 25 | 22 | 22 | 21 | 20 | 20 | 20 | 21 | 21 | 21 | 22 | 23 | 24 | 22 | 23 | 23 |
Feels °C | 26 | 27 | 27 | 27 | 28 | 21 | 22 | 19 | 15 | 15 | 16 | 17 | 17 | 18 | 22 | 28 | 29 | 23 | 24 | 24 |
Swell 1 Height (m) Direction Period (s) | SE 9 | SSE 9 | SE 8 | SE 8 | SE 9 | SE 7 | SE 8 | SE 8 | E 12 | E 14 | SSE 9 | SE 18 | SE 16 | SE 14 | SE 13 | SE 12 | SE 12 | SE 13 | SE 12 | SE 13 |
| kJ | 147 | 264 | 177 | 149 | 193 | 102 | 100 | 55 | 44 | 14 | 8 | 79 | 1317 | 2630 | 2574 | 2597 | 2078 | 2483 | 2195 | 2140 |
Swell 2 Height (m) Direction Period (s) | E 12 | E 14 | E 14 | E 14 | E 13 | E 13 | E 12 | E 12 | E 15 | SE 9 | S 15 | SE 7 | E 11 | E 11 | E 10 | E 10 | SSE 18 | ESE 10 | E 13 | E 12 |
| kJ | 112 | 189 | 195 | 261 | 167 | 215 | 148 | 102 | 4 | 3 | 4 | 9 | 63 | 58 | 96 | 98 | 107 | 980 | 13 | 45 |
Swell 3 Height (m) Direction Period (s) | ENE 7 | ENE 7 | ENE 7 | NE 10 | — | S 6 | — | E 16 | E 15 | SSE 9 | — | SSE 9 | — | — | — | E 10 | SSE 18 | NE 8 | E 13 | E 12 |
| kJ | 9 | 10 | 10 | 4 | — | 10 | — | 5 | 17 | 8 | — | 8 | — | — | — | 94 | 64 | 28 | 30 | 101 |
Wind waves Height (m) Direction Period (s) | SSW 4 | S 7 | — | — | SSE 6 | NE 4 | NE 5 | NE 6 | NE 7 | ENE 8 | ENE 8 | ENE 8 | NE 8 | ENE 7 | NE 7 | NE 7 | — | — | E 10 | E 9 |
| kJ | 13 | 1 | — | — | 90 | 14 | 68 | 175 | 394 | 546 | 634 | 705 | 616 | 329 | 194 | 93 | — | — | 826 | 562 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 205 | 18 | 110 | 9 | 0 | 51 | 56 | 295 | 206 | 617 | 536 | 295 | 206 | 295 | 206 | 0 | 0 | 0 | 40 | 56 |
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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