
Surf Forecasts:
Onjuku surf forecast from 8 Aug 2026:
- Best quality surf: Sunday 9 Aug, 3AM (local time) - 5.5ft (1.7m), 14s period, ESE swell with glassy winds.
- Most powerful swell: Monday 10 Aug, 3PM (local time) - 8ft (2.5m), 12s period, ENE swell with 1,586 kJ wave energy.
- Next surfable swell (1★+): Sunday 9 Aug, 3AM (local time) - 5.5ft (1.7m), 14s period with ESE 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 09) at 3AM. The primary swell is predicted to be 1.7m and 14s period with a secondary swell of 0.9m and 11s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 2.5m 12s and forecast to arrive on Monday (Aug 10) at 3PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.9m 8s period and expected on Tuesday (Aug 11) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Sun 9th Aug) | 5.5ft (1.7m) 14s |
| Best Surf | 3AM (Sun 9th Aug) | 5.5ft (1.7m) 14s |
| Most Powerful | 3PM (Mon 10th Aug) | 8ft (2.5m) 12s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here, let’s get into it.
We’re looking at a solid stretch of surf coming up at Onjuku, though it’s not for the faint of heart. The first decent window hits Sunday morning, the 9th of August. We’ve got a solid 6ft of ESE groundswell (13 seconds) rolling in, and it’s glassy – that’s a beautiful start. The water temp is about average for this time of year, so no surprises there.
Sunday morning is a standout. That 6ft swell with glassy conditions is a real treat. The combined energy is pumping at 1131 (moderate to strong), so it’s got some punch. Keep in mind, this is an exposed spot, and at that size it's for experienced surfers only – over 5ft, so beginners should sit this one out. The crowd factor is “sometimes,” so it could get a bit busy.
By Monday the 10th, the swell bumps up to 7ft from the east, but the wind picks up to a cross-offshore breeze (15-18 mph). It’s still clean, but that wind is a bit of a hassle. The energy jumps to 1226 then later 2943 (strong to very strong) – a lot of power, but the quality takes a hit.
Tuesday morning the 11th looks like another highlight. The wind swings light WNW cross-offshore, the swell is 7ft from the east with an 11-second period, and conditions are clean. The energy is 1137 – moderate to strong – and the report calls it excellent for experienced surfers. This is the kind of morning you set the alarm for.
After Tuesday afternoon, things go a bit ragged. The wind gets messy, and we hit a gap of several quiet days mid-week. Wednesday and Thursday are small and choppy, not worth paddling out for. By Friday the 14th, we get a pulse of 7ft from the east, but the wind is cross or cross-off and the energy is up there (1537), though the quality is marginal. Not a standout, but a possible early session if you’re keen.
The weekend of the 15th-16th stays in the 6ft to 7ft range from the east, but the wind is strong (15-22 mph). Clean, but those stiff winds make it a workout. For a beach break like this, the setup is starting to look more interesting for kite surfing than paddle surfing.
The next real standout comes on Wednesday the 19th of August. Swell holds at 7ft from the east, period drops to 8 seconds, but the wind is light cross-off in the morning and glassy-adjacent in the afternoon. The energy is 1107 (moderate to strong) and the report says excellent for experienced surfers. This is another top pick – just watch the shorter period, which can make the waves a bit dumpy at a beach break. Perfect for reefs or points, but here it’s still good if you’re ready for a steeper drop.
After that, the last week of the forecast trails off. The 20th through 24th sees smaller swell (2ft to 7ft) with onshore or cross-onshore winds and dropping energy. There’s a small, glassy morning on the 22nd with 4ft of ESE swell – a gentle session for a longboard, but nothing to write home about.
Best on offer: Sunday morning the 9th for that glassy groundswell, and Wednesday the 19th for cleaner conditions on a solid size. Both are for experienced surfers only.
Rusty.
Short Range ForecastLight rain (total 4mm), mostly falling on Tue afternoon. Warm (max 28°C on Sun morning, min 22°C on Mon night). Winds increasing (calm on Sat night, fresh winds from the SW by Tue afternoon). | Days 5-7 Weather SummaryHeavy rain (total 61mm), heaviest during Tue night. Warm (max 28°C on Thu afternoon, min 24°C on Tue night). Mainly fresh winds. | ||||||||||||||||||
Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | Thursday 13 | Friday 14 | ||||||||||||||
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) | ESE 14 | ESE 13 | ESE 13 | ESE 12 | E 12 | ENE 12 | ENE 10 | E 11 | E 12 | E 11 | E 10 | E 9 | E 9 | E 10 | E 9 | E 9 | E 10 | E 10 | E 10 |
Wave Graph | |||||||||||||||||||
1053 | 998 | 903 | 794 | 1103 | 1586 | 1341 | 970 | 1058 | 291 | 228 | 162 | 185 | 307 | 332 | 427 | 882 | 815 | 1092 | |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | glassy | cross | off | cross-off | cross-off | off | cross-off | cross-on | on | cross | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross | cross-off |
High Tide | 10:43PM1.31m | 4:10PM1.23m | 00:23AM1.32m | 4:33PM1.30m | 1:48AM1.37m | 4:57PM1.35m | 2:54AM1.44m | 5:21PM1.37m | 3:50AM1.49m | 5:43PM1.38m | 4:40AM1.50m | 6:04PM1.38m | |||||||
Low Tide | 7:36AM0.23m | 7:43PM1.16m | 8:40AM0.12m | 8:57PM1.09m | 9:31AM0.04m | 9:44PM0.99m | 10:15AM0.00m | 10:23PM0.88m | 10:54AM0.03m | 11:01PM0.75m | 11:29AM0.11m | 11:38PM0.63m | |||||||
— | 4:52 | — | — | 4:52 | — | — | 4:54 | — | — | 4:54 | — | — | 4:56 | — | — | 4:56 | — | — | |
6:36 | — | 6:35 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:29 | — | |
mm | — | — | — | — | — | — | — | — | 4 | 24 | 9 | 1 | 2 | 2 | — | 7 | 6 | 10 | 4 |
Temp °C | 25 | 28 | 27 | 25 | 26 | 26 | 23 | 25 | 25 | 25 | 26 | 27 | 25 | 27 | 28 | 26 | 28 | 27 | 26 |
Feels °C | 28 | 30 | 28 | 27 | 25 | 23 | 21 | 24 | 24 | 23 | 28 | 29 | 28 | 29 | 30 | 29 | 29 | 28 | 28 |
Swell 1 Height (m) Direction Period (s) | ESE 14 | ESE 13 | ESE 13 | ESE 12 | E 12 | E 12 | ENE 10 | E 11 | E 12 | E 11 | E 10 | E 9 | E 9 | E 10 | E 9 | E 9 | E 10 | S 9 | E 10 |
1053 | 998 | 903 | 794 | 1103 | 1166 | 800 | 970 | 1058 | 291 | 228 | 162 | 185 | 307 | 332 | 427 | 587 | 61 | 787 | |
Swell 2 Height (m) Direction Period (s) | S 11 | S 10 | S 10 | S 10 | S 11 | S 11 | S 10 | S 10 | NE 9 | ENE 11 | S 10 | SSW 11 | S 10 | S 10 | S 10 | S 10 | S 9 | SE 15 | S 10 |
231 | 133 | 141 | 104 | 86 | 88 | 78 | 77 | 287 | 207 | 78 | 150 | 106 | 73 | 51 | 48 | 43 | 9 | 65 | |
Swell 3 Height (m) Direction Period (s) | SW 14 | — | SW 12 | SW 12 | SW 12 | SW 11 | — | SSW 11 | SE 13 | S 10 | SSW 5 | ESE 5 | E 11 | SSE 11 | SSE 12 | SSE 11 | SSE 11 | S 21 | SE 20 |
29 | — | 90 | 23 | 37 | 103 | — | 90 | 26 | 75 | 7 | 18 | 81 | 13 | 13 | 11 | 25 | 9 | 15 | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | ENE 12 | ENE 10 | — | SSW 11 | S 5 | ESE 5 | — | — | NE 3 | — | — | E 10 | E 10 | E 10 |
— | — | — | — | — | 1586 | 1341 | — | 164 | 53 | 7 | — | — | 5 | — | — | 882 | 815 | 1092 | |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 9 | 0 | 56 | 0 | 56 | 51 | 51 | 0 | 18 | 9 | 68 | 0 | 0 | 51 | 51 | 0 | 206 | 557 | 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.











