
Surf Forecasts:
Onjuku surf forecast from 15 Jul 2026:
- Best quality surf: Sunday 19 Jul, 6AM (local time) - 4.5ft (1.3m), 9s period, ESE swell with glassy winds.
- Most powerful swell: Tuesday 21 Jul, 9PM (local time) - 5ft (1.5m), 11s period, E swell with 544 kJ wave energy.
- Next surfable swell (1★+): Sunday 19 Jul, 6AM (local time) - 4.5ft (1.3m), 9s 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 (Jul 19) at 6AM. The primary swell is predicted to be 1.3m and 9s period with a secondary swell of 0.2m and 8s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Onjuku in the next 16 days are 1.5m 11s and forecast to arrive on Tuesday (Jul 21) 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 1.1m 5s period and expected on Wednesday (Jul 22) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Sun 19th Jul) | 4.5ft (1.3m) 9s |
| Best Surf | 6AM (Sun 19th Jul) | 4.5ft (1.3m) 9s |
| Most Powerful | 9PM (Tue 21st Jul) | 5ft (1.5m) 11s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright folks, Rusty here.
First off, I’ll be straight with you – the next week or so is looking pretty grim for a proper paddle at Onjuku. The water temp is sitting at a normal 78° for this time of year, so no surprises there, but the swell is small and messy with onshore winds messing up the surface. There’s a long patch of poor conditions from the 15th through the 18th, with tiny waves around 2 ft to 3 ft and weak energy (84 to 216). Not worth paddling out unless you’re desperate for a float.
We start to see a glimmer of hope on the morning of the 20th. That Monday brings a glassy morning with a clean 4 ft easterly swell, period at 10 seconds, and moderate energy (290). It’s small but clean – a good one for beginners or a longboard cruise. The wind is glassy, so the surface will be smooth. The 21st Tuesday morning is similar, with 5 ft easterly groundswell and glassy conditions (414 energy), but the swell gets a bit bumpy in the afternoon as the wind swings onshore.
The real spark comes late on the 23rd and into the 24th. Thursday the 23rd morning has a clean 4 ft easterly swell with a cross-offshore breeze from the NNE (399 energy). Friday the 24th morning stays clean with 3 ft easterly swell and light cross-offshore wind (278 energy), and the afternoon holds 3 ft but still clean. These are the best windows in the first week – small but clean, fun for a cruisy session.
Now, hold onto your board – the end of the month is looking serious. On the 29th of July, Wednesday morning, we’ve got a 5 ft southeasterly swell with a very long 15-second period, but the wind is cross-onshore, so it’s still a bit grotty. The energy is big (857). That afternoon, the swell bumps to 5 ft, same direction, long period, and the wind goes cross-shore, making it cleaner (1244 energy). This is more for the experienced crew – 5 ft with that kind of period will have some punch.
Thursday the 30th is the standout. Morning sees 6 ft southeasterly groundswell, 15-second period, and a clean cross-offshore wind from the NE (1739 energy). The afternoon gets even better: 7 ft southeasterly swell, 16-second period, and clean cross-offshore wind (2942 energy). That’s proper groundswell – long, powerful lines. At over 7 ft, this is only for experts. The break will be powerful, and with that long period, Onjuku, being a beach break, might close out a bit, so look for a bank that holds. The wind is clean, though, so the surface will be glassy. This is the best on offer in the whole 16-day window.
So, to sum it up: the first week is mostly weak and windy, with a couple of clean small windows on the 20th, 21st, 23rd, and 24th. The real standout is the 30th of July – big, clean, powerful groundswell. Stay safe out there.
Rusty.
Short Range ForecastLight rain (total 3mm), mostly falling on Thu night. Warm (max 28°C on Wed afternoon, min 25°C on Fri night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 29°C on Tue morning, min 24°C on Sat night). Wind will be generally light. | ||||||||||||||||||||
Wed 15 | Thursday 16 | Friday 17 | Saturday 18 | Sunday 19 | Monday 20 | Tuesday 21 | |||||||||||||||
PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | |
Swell Height Map | |||||||||||||||||||||
Wave Height (m) Direction Period (s) | E 8 | E 9 | ESE 8 | ESE 9 | E 8 | E 8 | E 8 | E 8 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | E 9 | E 10 | E 10 | E 10 | E 10 | E 11 | E 11 | E 11 |
Wave Graph | |||||||||||||||||||||
31 | 96 | 96 | 99 | 90 | 92 | 90 | 69 | 172 | 180 | 268 | 211 | 280 | 202 | 260 | 277 | 365 | 400 | 457 | 534 | 524 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | cross-on | on | on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | on | on | glassy | glassy | on | cross-on | glassy | on | cross-on | cross-on |
High Tide | 6:24PM1.37m | 4:33AM1.52m | 6:54PM1.36m | 5:24AM1.49m | 7:20PM1.34m | 6:15AM1.41m | 7:45PM1.33m | 7:06AM1.30m | 8:08PM1.33m | 8:01AM1.17m | 8:32PM1.33m | 9:07AM1.04m | 8:57PM1.32m | 10:41AM0.95m | |||||||
Low Tide | 11:12PM0.96m | 11:51AM-0.03m | 11:55PM0.87m | 12:29PM0.08m | 00:40AM0.77m | 1:04PM0.23m | 1:26AM0.69m | 1:34PM0.40m | 2:16AM0.63m | 2:01PM0.57m | 3:11AM0.58m | 2:24PM0.72m | 4:14AM0.54m | ||||||||
— | — | 4:35 | — | — | 4:35 | — | — | 4:35 | — | — | 4:37 | — | — | 4:37 | — | — | 4:37 | — | — | 4:39 | |
6:52 | — | — | 6:52 | — | — | 6:52 | — | — | 6:52 | — | — | 6:51 | — | — | 6:51 | — | — | 6:50 | — | 6:50 | |
mm | — | — | — | — | 2 | — | — | 1 | — | — | — | — | — | — | — | — | — | — | — | 1 | 2 |
Temp °C | 28 | 26 | 28 | 28 | 26 | 27 | 27 | 25 | 27 | 26 | 25 | 27 | 27 | 25 | 27 | 27 | 26 | 29 | 28 | 26 | 28 |
Feels °C | 30 | 27 | 31 | 31 | 29 | 29 | 29 | 28 | 29 | 27 | 27 | 29 | 29 | 28 | 30 | 30 | 30 | 32 | 30 | 30 | 32 |
Swell 1 Height (m) Direction Period (s) | E 8 | E 9 | ESE 8 | ESE 9 | E 8 | E 8 | E 8 | SE 5 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | E 9 | E 10 | E 10 | E 10 | E 10 | E 11 | E 11 | E 11 |
31 | 96 | 96 | 99 | 90 | 92 | 90 | 25 | 172 | 180 | 268 | 211 | 280 | 202 | 260 | 277 | 365 | 400 | 457 | 534 | 524 | |
Swell 2 Height (m) Direction Period (s) | SSW 9 | SSE 9 | SSW 9 | SSW 8 | SE 10 | E 6 | SE 9 | E 8 | SE 9 | SE 8 | SE 8 | SE 9 | S 8 | SSE 7 | SSE 8 | SE 8 | SSE 8 | SSE 8 | SSE 8 | SSE 8 | S 7 |
28 | 8 | 7 | 7 | 14 | 17 | 22 | 69 | 20 | 34 | 15 | 38 | 11 | 21 | 26 | 17 | 13 | 13 | 12 | 11 | 10 | |
Swell 3 Height (m) Direction Period (s) | ESE 9 | SE 11 | S 14 | SE 11 | SSW 8 | SE 10 | SSW 8 | SE 8 | SW 7 | S 9 | S 8 | S 8 | SE 13 | S 8 | S 7 | S 7 | SE 11 | SW 6 | ESE 11 | WSW 8 | — |
16 | 5 | 4 | 18 | 6 | 23 | 6 | 25 | 2 | 2 | 5 | 5 | 6 | 10 | 4 | 4 | 5 | 1 | 12 | 6 | — | |
Wind waves Height (m) Direction Period (s) | S 4 | S 5 | S 5 | S 5 | SSE 5 | SSE 5 | SSE 5 | — | SSW 4 | — | — | SSE 8 | SSE 8 | SSW 3 | — | S 3 | S 3 | — | SSW 2 | S 3 | — |
9 | 59 | 31 | 21 | 33 | 42 | 36 | — | 3 | — | — | 75 | 69 | 2 | — | 1 | 1 | — | 1 | 3 | — | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 9 | 17 | 17 | 9 | 9 | 206 | 103 | 9 | 9 | 103 | 9 | 9 | 9 | 0 | 0 | 9 | 9 | 0 | 9 | 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.











