Surf Forecasts:
Onjuku surf forecast from 20 Jul 2026:
- Best quality surf: Thursday 23 Jul, 9AM (local time) - 2.5ft (0.8m), 10s period, E swell with cross-offshore winds.
- Most powerful swell: Monday 20 Jul, 9PM (local time) - 4ft (1.2m), 11s period, E swell with 335 kJ wave energy.
- Next surfable swell (1★+): Thursday 23 Jul, 9AM (local time) - 2.5ft (0.8m), 10s 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 Thursday (Jul 23) at 9AM. The primary swell is predicted to be 0.8m and 10s period with a secondary swell of 0.4m and 5s. Another secondary swell of 0.7m 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 1.2m 11s and forecast to arrive on Monday (Jul 20) at 9PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.6m 4s period and expected on Friday (Jul 24) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Thu 23rd Jul) | 2.5ft (0.8m) 10s |
| Best Surf | 9AM (Thu 23rd Jul) | 2.5ft (0.8m) 10s |
| Most Powerful | 9PM (Mon 20th Jul) | 4ft (1.2m) 11s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright folks, let’s talk about Onjuku. The next week and a half is a bit of a mixed bag, but there’s a few windows where it’ll get real good. Right now, we’re looking at a flat spell from today through Wednesday – nothing but cross-onshore chop and tiny waves. That’s a solid three-day gap with no surf worth paddling out for. The water’s sitting at 78°, which is bang on average for this time of year, so no surprises there.
Thursday the 23rd and Friday the 24th bring a little bump – small 2ft to 3ft swells from the east, clean with cross-off winds, but it’s weak and inconsistent. The combined energy is only around 112-172, so really just ankle-biters. Saturday the 25th is a non-starter with storms and cross-shore junk. Sunday the 26th and Monday the 27th stay marginal – a bit more size but still messy onshore winds.
Then, Tuesday the 28th is where it all comes together. A solid 4ft groundswell from the SSW, with a long 14-second period, pushes into the exposed beach. The combined energy jumps to 732 in the morning and 775 in the afternoon – that’s moderate but punchy. Morning winds are light cross-off, clean, and by afternoon it turns glassy. That’s the kind of day you wait for – clean, lined-up sets, and the 14-second period means proper waves with good shape. The swell direction (SSW) is close to the optimum SSE, so it’ll wrap in nicely. This is the standout of the whole outlook.
Wednesday the 29th holds similar size (4ft, 13-14s) with moderate energy around 509-535, but the wind switches to cross-shore in the afternoon, so grab the morning session when it’s still clean. After that, Thursday the 30th through Friday the 31st drops off again – small, onshore, no good. Saturday August 1st has a bit of size (4-4ft) but the wind is howling out of the NE, so it’s chopped.
Sunday August 2nd offers a surprise: a 2ft swell from the east with a very long 16-second period and offshore NNE winds at 12 mph. The combined energy is 310 – moderate – and the wind is offshore, so it’ll be clean. The long period is great for points and reefs, but at a beach break like Onjuku it might be a bit too straight. Still, if you’re hungry, it’s worth a look. After that, Monday the 3rd and Tuesday the 4th are back to wind-blown rubbish.
So, bottom line: Tuesday the 28th is the day to pencil in – glassy, good-sized, and long-period. Wednesday morning is also solid. The rest of the window is mostly wait-and-see. Keep an eye on that Sunday the 2nd as a wildcard.
Rusty.
Short Range ForecastMostly dry. Warm (max 30°C on Wed morning, min 25°C on Mon night). Wind will be generally light. | Days 4-6 Weather SummaryModerate rain (total 17mm), heaviest on Fri night. Warm (max 29°C on Thu afternoon, min 23°C on Sat night). Wind will be generally light. | ||||||||||||||||||||
Monday 20 | Tuesday 21 | Wednesday 22 | Thursday 23 | Friday 24 | Saturday 25 | Sunday 26 | |||||||||||||||
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 | E 8 | E 11 | E 10 | E 10 | E 10 | E 10 | E 10 | E 10 | E 10 | E 9 | E 9 | E 9 | SE 11 | SE 16 | SE 16 | SE 16 | SE 10 | SE 15 | SE 15 | ESE 6 |
Wave Graph  | |||||||||||||||||||||
 kJ | 119 | 116 | 329 | 257 | 247 | 196 | 196 | 156 | 121 | 113 | 81 | 80 | 57 | 57 | 66 | 65 | 69 | 50 | 55 | 64 | 77 |
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-on | cross-on | cross-on | cross-on | cross-on | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross | cross-off | on | on | cross-off |
High Tide | 8:32PM1.33m | 9:07AM1.04m | 8:57PM1.32m | 10:41AM0.95m | 9:26PM1.31m | 10:06PM1.28m | 11:05PM1.26m | 4:30PM1.13m | 00:24AM1.25m | 4:42PM1.19m | 1:35AM1.28m | ||||||||||
Low Tide | 2:01PM0.57m | 3:11AM0.58m | 2:24PM0.72m | 4:14AM0.54m | 2:41PM0.85m | 5:28AM0.50m | 6:45AM0.44m | 7:51AM0.37m | 7:16PM1.10m | 8:43AM0.30m | 8:40PM1.07m | ||||||||||
 | |  | | | | | | | | |  |  | | |  | |  | | | | |
 | 4:37 | — | — | 4:37 | — | — | 4:39 | — | — | 4:39 | — | — | 4:39 | — | — | 4:41 | — | — | 4:41 | — | — |
 | — | 6:51 | — | — | 6:50 | — | — | 6:50 | — | — | 6:49 | — | — | 6:47 | — | — | 6:47 | — | — | 6:46 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | 3 | — | — | 7 | 4 | 3 | — | — | — | 13 |
Temp °C | 28 | 28 | 26 | 29 | 29 | 26 | 30 | 29 | 27 | 28 | 29 | 27 | 27 | 26 | 25 | 25 | 25 | 24 | 26 | 27 | 26 |
Feels °C | 31 | 29 | 29 | 32 | 31 | 29 | 33 | 31 | 31 | 34 | 34 | 33 | 30 | 28 | 29 | 29 | 28 | 27 | 28 | 30 | 30 |
Swell 1 Height (m) Direction Period (s) | E 9 | E 8 | E 11 | E 10 | E 10 | E 10 | E 10 | E 10 | E 10 | E 10 | E 9 | E 9 | E 9 | E 9 | E 8 | E 8 | SE 10 | E 5 | SE 11 | SE 10 | ESE 6 |
| kJ | 119 | 116 | 329 | 257 | 247 | 196 | 196 | 156 | 121 | 113 | 81 | 80 | 57 | 56 | 35 | 35 | 49 | 45 | 55 | 64 | 77 |
Swell 2 Height (m) Direction Period (s) | S 7 | E 14 | SSE 8 | SSE 8 | SSE 8 | SSE 8 | SSW 4 | SSE 7 | SSE 10 | SSW 5 | SSW 4 | SE 10 | SE 9 | SE 11 | SE 10 | SE 10 | SE 16 | SE 10 | SE 15 | SE 15 | SE 10 |
| kJ | 25 | 59 | 13 | 13 | 12 | 6 | 12 | 5 | 10 | 7 | 6 | 24 | 22 | 57 | 54 | 48 | 63 | 50 | 55 | 54 | 54 |
Swell 3 Height (m) Direction Period (s) | S 7 | SSE 7 | SE 11 | SE 11 | SE 11 | ESE 11 | SSE 8 | SE 11 | SSE 7 | SE 10 | SE 10 | S 5 | SE 18 | SE 17 | SE 16 | SE 16 | S 8 | E 8 | E 8 | E 8 | S 11 |
| kJ | 4 | 4 | 5 | 20 | 19 | 12 | 6 | 5 | 5 | 25 | 25 | 4 | 49 | 43 | 66 | 65 | 5 | 21 | 12 | 12 | 37 |
Wind waves Height (m) Direction Period (s) | SSW 3 | SSW 4 | SSW 4 | SSW 4 | SSW 4 | SSW 4 | SW 5 | SSW 4 | SSW 4 | SW 5 | — | — | NE 3 | ENE 4 | ENE 4 | ENE 4 | E 8 | — | E 6 | ESE 6 | — |
| kJ | 4 | 10 | 5 | 6 | 14 | 10 | 22 | 16 | 7 | 27 | — | — | 6 | 9 | 10 | 6 | 69 | — | 54 | 52 | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 9 | 17 | 23 | 9 | 1475 | 9 | 9 | 914 | 9 | 0 | 0 | 0 | 56 | 57 | 0 | 0 | 56 | 0 | 9 | 9 | 73 |
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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