Surf Forecasts:
Onjuku surf forecast from 30 Aug 2026:
- Best quality surf: Sunday 6 Sep, 3AM (local time) - 8ft (2.5m), 8s period, E swell with offshore winds.
- Most powerful swell: Sunday 6 Sep, 3AM (local time) - 8ft (2.5m), 8s period, E swell with 970 kJ wave energy.
- Next surfable swell (1★+): Sunday 30 Aug, 6PM (local time) - 1.5ft (0.5m), 11s 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 Sunday (Aug 30) at 6PM. The primary swell is predicted to be 0.5m and 11s period with a secondary swell of 0.5m and 5s. 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 8s and forecast to arrive on Sunday (Sep 06) at 3AM. Winds are predicted to be offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.5m 6s period and expected on Friday (Sep 04) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6PM (Sun 30th Aug) | 1.5ft (0.5m) 11s |
| Best Surf | 3AM (Sun 6th Sep) | 8ft (2.5m) 8s |
| Most Powerful | 3AM (Sun 6th Sep) | 8ft (2.5m) 8s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here, and I'm lookin' at the outlook for our local spot, Onjuku. The water is a touch warmer than usual for this time of year, sitting at 82°, which is a nice bonus.
Starting off, we're in a bit of a slump. The first few days, from Sunday the 30th through Monday the 31st, are pretty weak. There’s knee-high dribble at best, with messy conditions and onshore breezes. Honestly, you’d be doin' more paddlin' than surfin'. It’s a little frustratin', but we know how it goes.
Tuesday the 1st of September is where things start to perk up. The morning session is the real standout of this first week. We’ve got a clean, chest-high long-period groundswell comin' out of the ESE, and a moderate offshore wind from the NNE tidyin' everything up. The combined energy is up at a solid moderate 282. It's not pumpin', but it's got shape and it’s clean. Just be aware it's an inconsistent break, so you'll be waitin' for the sets, but it'll be worth it.
Wednesday mornin' the 2nd is another gem. The wind goes glassy, and we’ve got a clean 3 ft wave from the ESE. It's a proper session for the logs or a mid-length. The swell energy is still moderate at 222. Savor that mornin' because the afternoon gets messy with a southerly onshore that blows it out.
From Thursday the 3rd through most of Friday the 4th, it turns pretty poor again. Strong winds and buildin' chop make for a rough go. The combined energy drops right back down.
Now, lookin' at the second week, there’s a big pulse of energy arrivin'. Sunday the 6th of September sees some serious size on the charts, with the combined energy spikin' way up into the thousands (1250). We’re lookin' at 5 ft to 5 ft of long-period swell from the SSE, but it's heavily cross-offshore and the conditions are described as marginal. The period is 14-15 seconds, which is a very long groundswell. For a beach break like Onjuku, that long period can make it wall up and close out fast. It’s goin' to be powerful, lumpy, and more for the experienced crew if they can find a bank. Not a beginner's day at all.
This big, messy energy carries through the week to the 10th and 11th of September, with the swell stayin' over 5 ft and the winds messy, often cross or cross-on. It’s turbulent, and the quality is poor for a clean surf.
The true standout of this whole 16-day window is absolutely Tuesday the 1st of September morning at Onjuku. The combination of clean, offshore wind and a reasonable long-period groundswell from a good direction makes it the pick of the bunch. The Wednesday morning glass-off is the runner-up.
Overall, don't get too excited about the massive swell in week two. It looks powerful but messy. For clean, fun waves, your best bet is that window at the start of September.
Stay patient, and keep an eye on the forecast.
Rusty.
Short Range ForecastMostly dry. Warm (max 27°C on Tue morning, min 24°C on Sun afternoon). Wind will be generally light. | Days 5-7 Weather SummaryHeavy rain (total 31mm), heaviest during Sat morning. Warm (max 29°C on Thu morning, min 21°C on Sat morning). Winds increasing (light winds from the NNE on Thu night, fresh winds from the NE by Sat morning). | |||||||||||||||||||
Sun 30 | Monday 31 | Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | Saturday 5 | ||||||||||||||
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 11 | E 11 | E 11 | ESE 14 | ESE 12 | ESE 12 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | ESE 11 | E 10 | S 8 | SSE 6 | SSE 6 | SSE 6 | E 10 | E 7 | NE 7 | E 8 |
Wave Graph | ||||||||||||||||||||
60 | 57 | 57 | 73 | 175 | 193 | 214 | 170 | 116 | 111 | 121 | 73 | 84 | 94 | 75 | 41 | 30 | 316 | 278 | 815 | |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | off | cross-off | cross-off | off | off | cross-off | glassy | glassy | on | cross-on | on | on | cross-on | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off |
High Tide | 5:51PM1.42m | 5:58AM1.39m | 6:10PM1.43m | 6:41AM1.32m | 6:31PM1.44m | 7:30AM1.23m | 6:53PM1.43m | 8:31AM1.12m | 7:17PM1.40m | 10:14AM1.02m | 7:46PM1.36m | 8:26PM1.30m | ||||||||
Low Tide | 11:54PM0.43m | 12:02PM0.43m | 00:30AM0.36m | 12:27PM0.56m | 1:09AM0.32m | 12:52PM0.70m | 1:54AM0.31m | 1:12PM0.84m | 2:52AM0.34m | 1:18PM0.97m | 4:13AM0.36m | |||||||||
— | — | 5:09 | — | — | 5:09 | — | — | 5:11 | — | — | 5:11 | — | — | 5:11 | — | — | 5:13 | — | — | |
6:08 | — | — | 6:07 | — | — | 6:06 | — | — | 6:05 | — | — | 6:04 | — | — | 6:01 | — | — | 6:00 | — | |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | 5 | — | — | 8 | 18 | 6 | 4 |
Temp °C | 24 | 24 | 25 | 25 | 24 | 27 | 26 | 25 | 27 | 28 | 27 | 29 | 29 | 27 | 23 | 24 | 24 | 21 | 21 | 21 |
Feels °C | 27 | 27 | 26 | 26 | 25 | 29 | 29 | 30 | 30 | 30 | 31 | 30 | 30 | 29 | 22 | 23 | 23 | 18 | 18 | 19 |
Swell 1 Height (m) Direction Period (s) | E 5 | E 11 | E 11 | ESE 14 | ESE 12 | ESE 12 | ESE 11 | ESE 11 | ESE 10 | ESE 10 | ESE 11 | SE 6 | SE 6 | E 10 | SSE 6 | SSE 6 | SSE 6 | S 8 | ESE 8 | SSE 12 |
18 | 57 | 57 | 73 | 175 | 193 | 214 | 170 | 116 | 111 | 121 | 38 | 40 | 67 | 75 | 41 | 13 | 12 | 226 | 184 | |
Swell 2 Height (m) Direction Period (s) | E 11 | ENE 5 | SE 9 | E 11 | E 11 | NE 6 | ENE 6 | E 7 | E 7 | E 6 | SSW 8 | E 10 | E 10 | SSW 8 | E 9 | ESE 9 | SE 9 | SSE 16 | SSE 14 | SSE 15 |
60 | 7 | 22 | 56 | 36 | 35 | 31 | 44 | 44 | 41 | 22 | 73 | 71 | 14 | 42 | 28 | 28 | 26 | 80 | 133 | |
Swell 3 Height (m) Direction Period (s) | SSW 7 | SSW 7 | NE 7 | SE 9 | SSW 9 | SSW 8 | SSW 9 | SSW 8 | SSW 8 | SSW 8 | SE 10 | SE 10 | SE 10 | SE 10 | SE 9 | SE 9 | E 10 | E 13 | SSW 9 | SW 10 |
21 | 10 | 16 | 22 | 16 | 24 | 25 | 14 | 22 | 22 | 15 | 15 | 25 | 23 | 21 | 21 | 30 | 14 | 15 | 25 | |
Wind waves Height (m) Direction Period (s) | ENE 5 | NE 4 | NE 4 | NE 6 | NE 5 | NE 6 | — | — | — | — | SE 6 | S 8 | S 8 | SSE 6 | NE 5 | ENE 6 | ENE 6 | E 7 | NE 7 | E 8 |
20 | 9 | 9 | 45 | 57 | 68 | — | — | — | — | 52 | 64 | 84 | 94 | 47 | 139 | 122 | 316 | 278 | 815 | |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 0 | 0 | 16 | 56 | 0 | 0 | 0 | 0 | 0 | 9 | 18 | 9 | 9 | 2 | 51 | 51 | 206 | 240 | 571 | 82 |
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.











