Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 pm 09 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
27.0° C
0.3° 

Onjuku surf forecast is for near shore open water. Breaking waves will often be smaller at less exposed spots.


Onjuku surf forecast from 9 Aug 2026:

  • Best quality surf: Sunday 9 Aug, 6PM (local time) - 5.5ft (1.7m), 12s period, ESE swell with cross-offshore winds.
  • Most powerful swell: Saturday 15 Aug, 3PM (local time) - 10ft (3.0m), 12s period, E swell with 2,344 kJ wave energy.
  • Next surfable swell (1★+): Sunday 9 Aug, 6PM (local time) - 5.5ft (1.7m), 12s 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 6PM. The primary swell is predicted to be 1.7m and 12s period with a secondary swell of 0.8m 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 3.0m 12s and forecast to arrive on Saturday (Aug 15) 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 2.0m 8s period and expected on Tuesday (Aug 11) at 6AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 6PM (Sun 9th Aug)5.5ft (1.7m) 12s
Best Surf 6PM (Sun 9th Aug)5.5ft (1.7m) 12s
Most Powerful 3PM (Sat 15th Aug)10ft (3.0m) 12s

Table - best surf conditions forecast for Onjuku over the next 16 days.


The Lowdown

G’day, Rusty here.

Let’s be straight with you. The next couple of weeks are a mixed bag for Onjuku. There’s a solid pulse of swell early on, but the winds are going to be fighting us for most of it. We’ve got a real window of opportunity in the first few days, then things get messy and drop right off. There’s a long stretch in the middle there where I’d rather be doing anything else, and then only a glimmer of hope at the very end.

The water’s sitting at a warm 80°, which is just about spot on for this time of year, so you won’t need a thick suit.

Sunday morning, August 9th, is the pick of the first run. We’ve got a clean 6ft east-southeast swell rolling in with a 13-second period, and it’s glassy. The energy is strong (1131), and conditions are going to be excellent for anyone with a bit of experience. This is your best chance to get a proper session in before the wind gets on it. Later that afternoon, the wind swings east and puts a bit of chop on it, so get out early.

Monday, August 10th sees the swell bump up to 7ft, but a fresh northeast breeze at 19 mph makes it cross-off and a bit lumpy. It’s still clean-ish, but the quality drops off. This is pushing towards the bigger side, so if you’re not comfortable out there, give it a miss.

Tuesday morning, August 11th is another standout. The swell is still a solid 7ft from the east with a 10-second period, and we get a light offshore north wind. The energy is cranking (1532), and it’s clean. This is proper condition for experienced surfers. The afternoon turns to rubbish though, with a cross-onshore southwest wind and a choppy mess.

Then we hit the doldrums. From Tuesday afternoon through to Friday, August 14th, it’s a mix of poor surf and onshore winds. The swell drops to 4ft, the energy weakens, and the wind is all over the place. Thursday and Friday have some clean-ish mornings but the swell is just too weak and short-period to be worth the paddle.

The weekend of the 15th and 16th is a write-off. Storms and onshore winds kill it. The swell picks back up to 6ft on Sunday the 16th, but it’s stormy and messy.

The start of the next week, Monday, August 17th, has size at 5ft but a fresh cross-off wind at 19 mph makes it difficult. Not worth it.

Then the real gap hits. From Monday afternoon, August 17th, right through to Saturday, August 23rd, it’s poor. The swell fades away, the wind goes onshore and southerly, and the energy just dies. There’s a long stretch of nothing here – a full five or six days where you’re better off waxing your board and just looking at the ocean.

There is a tiny glimmer at the very end. Sunday morning, August 23rd, sees a small 3ft south swell with glassy conditions and decent energy (329). It’s small, but it might have a few fun ones if you’re desperate. And then Monday morning, August 24th is totally flat and glassy with a 2ft east-southeast groundswell. It’s clean, but tiny.

So, in short: get out there Sunday morning the 9th or Tuesday morning the 11th. That’s your window. After that, it’s a long blank run, which is pretty normal for this area. The forecasts can change, so keep an eye on it, but don’t hold your breath.

Rusty.

Short Range Forecast

Moderate rain (total 19mm), heaviest on Wed morning. Warm (max 28°C on Sun afternoon, min 22°C on Mon night). Mainly fresh winds.

Days 5-7 Weather Summary

Heavy rain (total 36mm), heaviest during Thu night. Warm (max 28°C on Thu morning, min 24°C on Wed night). Wind will be generally light.

Sun
9
Monday
10
Tuesday
11
Wednesday
12
Thursday
13
Friday
14
Saturday
15
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
3
2
2
2
2
4
2
0
1
2
2
1
0
2
3
2
3
2
3
2
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
1.7
ESE
13
1.6
ESE
12
2.1
E
12
2.1
E
11
2.2
ENE
10
1.9
ENE
10
1.6
E
11
1.3
ENE
11
1.3
E
10
1
E
9
1.1
E
9
1.4
E
9
1.5
E
10
1.7
E
10
1.9
E
10
1.7
E
10
1.7
E
10
2.3
E
11
3
E
12
2.1
E
10
Wave Graph
Metric surfscale
Energy kJ
903
794
1227
1095
860
739
663
427
312
162
196
318
400
580
682
533
567
1201
2344
890
Wind (km/h)
15
E
15
NNE
30
NNE
30
NE
25
NNE
15
N
15
NW
20
S
20
ESE
15
E
15
NE
20
NNE
25
NE
20
NNE
20
N
20
NE
20
N
25
NNE
20
NE
10
SE
Wind State
cross
cross-off
cross-off
cross-off
off
off
cross-off
on
cross
cross-off
cross-off
cross-off
cross-off
cross-off
off
cross-off
off
cross-off
cross-off
cross-on
High Tide
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
5:27AM1.47m
6:24PM1.39m
Low Tide
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
12:00PM0.24m
00:15AM0.53m
part cloud
part cloud
part cloud
clear
part cloud
part cloud
rain showers
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
rain showers
thunderstorm
light rain
thunderstorm
thunderstorm
thunderstorm
thunderstorm
rain showers
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
4:52
4:54
4:54
4:56
4:56
4:56
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:35
6:32
6:31
6:30
6:30
6:29
6:28
 mm
2
9
8
3
5
1
1
13
2
6
1
4
1
2
Temp °C
28
25
26
26
24
27
27
25
26
27
25
28
28
26
25
26
25
26
27
26
Feels °C
29
27
25
25
22
27
27
25
27
28
27
28
28
28
26
27
26
26
28
30
  • Map Icons:
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  • Live Wave Height (m)
  • Live Wind Speed (km/h)
  • Surf Rating (10 Max)
  • Ocean Swells (m)
  • Wind Speed (km/h)
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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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