Surf Forecasts:
Onjuku surf forecast from 24 Aug 2026:
- Best quality surf: Thursday 27 Aug, 12PM (local time) - 3.5ft (1.0m), 11s period, S swell with cross-offshore winds.
- Most powerful swell: Monday 24 Aug, 3PM (local time) - 6ft (1.8m), 16s period, SSE swell with 1,634 kJ wave energy.
- Next surfable swell (1★+): Thursday 27 Aug, 12PM (local time) - 3.5ft (1.0m), 11s period with S 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 (Aug 27) at 12PM. The primary swell is predicted to be 1.0m and 11s period with a secondary swell of 0.5m and 10s. 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 1.8m 16s and forecast to arrive on Monday (Aug 24) at 3PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.7m 4s period and expected on Saturday (Aug 29) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12PM (Thu 27th Aug) | 3.5ft (1.0m) 11s |
| Best Surf | 12PM (Thu 27th Aug) | 3.5ft (1.0m) 11s |
| Most Powerful | 3PM (Mon 24th Aug) | 6ft (1.8m) 16s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here again. Let’s break it down.
We start with a real gem on Monday morning, the 24th: a clean, glassy 3ft SSE groundswell with a very long 18-second period. The water is warm at 82°F, about a degree and a half above normal for this time of year – noticeable but not crazy. The combined energy is moderate (944). That Monday morning session at Onjuku is the best of the whole forecast. The swell direction is right out of the SSE, which is exactly what this spot wants. It’s for intermediate paddlers, and the glassy conditions will make it silky.
Monday afternoon, the wind shifts cross-onshore and the swell picks up to 6ft, but it gets messy and strong (energy 1791). Tuesday through Thursday is a bust: onshore winds, lumpy, choppy, and some storms thrown in. The swell drops off hard.
From Friday the 28th through Sunday the 30th, it’s tiny: 2ft to 2ft E windswell, short 11-second period, and weak energy (112 to 229). The winds are clean, so the surface is nice, but there’s no push. Monday the 31st has another glassy morning with 2ft waves and very weak energy (95). It’s surfable, just barely.
Then Wednesday 2nd September brings a clean 3ft ESE swell with a 10-second period, light offshore winds, and moderate energy (299). The afternoon swings to a 3ft SSW groundswell with a 14-second period, clean, and energy at 383. This is a fun, clean session, though the long period might make it a bit straight at the beach break.
Thursday 3rd and Friday 4th: strong, clean winds but the swell is tiny (2ft to 3ft), energy low. Saturday 5th September sees a jump to 5ft ESE swell with a short 9-second period and moderate energy (494). The morning is clean, but the afternoon gets cross-shore chop. Marginal.
Sunday 6th and Monday 7th are 4ft to 4ft E swell, but onshore winds ruin it. Tuesday 8th finishes with a 6ft to 7ft E swell, long period, but fresh cross-onshore winds make it lumpy.
So the only real standout is Monday morning, 24th August. After that, there’s a long gap of poor conditions until a clean, modest session on 2nd September. The rest is too small, too windy, or both. If you’re into kite surfing, the stronger wind days with 5ft+ swell (like the 8th) might be more interesting than paddling.
Rusty.
Short Range ForecastMostly dry. Warm (max 29°C on Wed morning, min 26°C on Mon night). Winds increasing (calm on Mon morning, fresh winds from the SW by Wed afternoon). | Days 4-6 Weather SummaryHeavy rain (total 22mm), heaviest during Thu morning. Warm (max 28°C on Thu morning, min 24°C on Thu night). Wind will be generally light. | ||||||||||||||||||||
Monday 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | |||||||||||||||
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) | SSE 18 | SSE 16 | SSE 13 | SSE 13 | SSE 12 | S 12 | S 12 | SSW 12 | SSW 6 | SSE 10 | E 13 | E 13 | E 12 | SSW 8 | SW 6 | E 11 | E 11 | E 11 | E 11 | E 12 | E 12 |
Wave Graph  | |||||||||||||||||||||
 kJ | 459 | 1634 | 878 | 1025 | 755 | 273 | 185 | 150 | 123 | 123 | 173 | 163 | 151 | 103 | 149 | 62 | 61 | 61 | 62 | 98 | 99 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross | cross-on | cross-on | cross-on | cross-on | glassy | cross-off | cross-off | cross-off | cross-off | cross | cross-on |
High Tide | 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 | 5:17AM1.43m | 5:51PM1.42m | ||||||||
Low Tide | 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 | 11:35AM0.32m | 11:54PM0.43m | ||||||||
 | |  | | | |  | | |  | |  | | |  | | |  | | | | |
 | 5:03 | — | — | 5:05 | — | — | 5:05 | — | — | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — | 5:07 | — | — |
 | — | 6:16 | — | — | 6:15 | — | — | 6:14 | — | — | 6:13 | — | — | 6:12 | — | — | 6:09 | — | — | 6:08 | — |
mm | — | — | — | — | — | — | — | — | — | 6 | 5 | 8 | — | 1 | 2 | — | — | — | — | — | — |
Temp °C | 28 | 28 | 26 | 28 | 28 | 27 | 29 | 29 | 27 | 28 | 28 | 25 | 28 | 28 | 26 | 26 | 25 | 24 | 26 | 27 | 26 |
Feels °C | 30 | 29 | 28 | 28 | 28 | 27 | 30 | 29 | 26 | 31 | 29 | 28 | 29 | 30 | 30 | 26 | 24 | 24 | 27 | 28 | 30 |
Swell 1 Height (m) Direction Period (s) | SSE 12 | SSE 16 | SSE 13 | SSE 13 | SSE 12 | SSE 10 | SSE 9 | SSE 9 | SSE 9 | SSW 6 | S 10 | S 9 | SSW 6 | E 12 | SSW 7 | SSW 7 | S 8 | E 11 | E 11 | E 12 | E 12 |
| kJ | 226 | 1634 | 878 | 1025 | 755 | 241 | 185 | 146 | 90 | 55 | 156 | 106 | 48 | 103 | 77 | 57 | 35 | 61 | 62 | 98 | 99 |
Swell 2 Height (m) Direction Period (s) | SSE 18 | E 12 | SSE 16 | ESE 14 | ESE 13 | S 12 | S 12 | SSW 12 | SSW 12 | SSE 10 | E 13 | E 13 | E 12 | SE 9 | E 12 | E 11 | E 11 | S 8 | SSW 8 | SSW 8 | SSW 8 |
| kJ | 459 | 71 | 653 | 198 | 181 | 273 | 180 | 150 | 111 | 123 | 173 | 163 | 151 | 22 | 99 | 62 | 61 | 35 | 23 | 22 | 14 |
Swell 3 Height (m) Direction Period (s) | SSE 15 | ESE 8 | ESE 11 | E 11 | — | ESE 13 | ESE 12 | ESE 12 | E 12 | E 11 | SSE 10 | SSE 10 | SSE 9 | SE 15 | SSE 10 | SE 11 | SE 11 | SE 10 | SE 10 | SE 10 | SE 10 |
| kJ | 259 | 40 | 91 | 84 | — | 176 | 117 | 113 | 70 | 59 | 41 | 38 | 34 | 8 | 18 | 30 | 30 | 27 | 25 | 25 | 25 |
Wind waves Height (m) Direction Period (s) | — | SSW 8 | SW 4 | SSW 4 | SSW 4 | SW 5 | SW 5 | SSW 5 | SSW 6 | — | SSW 6 | SW 6 | SSW 6 | SSW 8 | SW 6 | NE 3 | ENE 4 | ENE 4 | E 4 | E 4 | SE 4 |
| kJ | — | 46 | 12 | 22 | 34 | 45 | 20 | 48 | 123 | — | 59 | 30 | 90 | 96 | 149 | 4 | 17 | 6 | 2 | 3 | 5 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 0 | 17 | 88 | 88 | 583 | 101 | 18 | 598 | 101 | 12 | 9 | 9 | 18 | 18 | 0 | 51 | 51 | 0 | 51 | 51 | 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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