Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 pm 11 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
27.7° C
1.0° 

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


Onjuku surf forecast from 11 Aug 2026:

  • Best quality surf: Sunday 16 Aug, 9AM (local time) - 11ft (3.5m), 11s period, E swell with cross-offshore winds.
  • Most powerful swell: Sunday 16 Aug, 12PM (local time) - 11ft (3.5m), 11s period, ENE swell with 2,767 kJ wave energy.
  • Next surfable swell (1★+): Wednesday 12 Aug, 6PM (local time) - 4ft (1.2m), 9s 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 Wednesday (Aug 12) at 6PM. The primary swell is predicted to be 1.2m and 9s period with a secondary swell of 0.6m and 6s. 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 3.5m 11s and forecast to arrive on Sunday (Aug 16) at 12PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 2.5m 7s period and expected on Sunday (Aug 16) at 9AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 6PM (Wed 12th Aug)4ft (1.2m) 9s
Best Surf 9AM (Sun 16th Aug)11ft (3.5m) 11s
Most Powerful12PM (Sun 16th Aug)11ft (3.5m) 11s

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


The Lowdown

Alright folks, Rusty here. Let's have a look at what's on the cards for Onjuku over the next couple of weeks.

Overall, it's a bit of a slow burner. The first few days are pretty much a write-off with messy, lumpy conditions. Things start to clean up around the middle of next week, but the real action looks to be a week away with a solid pulse of swell, though you'll need to pick your window carefully.

We kick off with nothing doing. Tuesday the 11th is a complete loss – onshore wind and poor surf. Wednesday the 12th and Thursday the 13th morning offer a glimmer of hope. On Thursday morning the 13th, we’ve got a clean 5-foot easterly swell with a moderate period of 9 seconds and a nice cross-offshore breeze. The combined energy is moderate at 446, so it’s more of a finesse session than a power day.

The real standout, without a doubt, is Monday the 17th. For the morning session, the forecast is glassy – absolute dead calm – with a clean 6-foot easterly swell (9-second period). The combined energy is a solid 514, meaning there’s some decent push behind it. The wind is a light southerly at just 3 mph, so the surface will be like a mirror. This is the best on offer: clean, user-friendly, and no crowds to worry about.

Now, there is a big pulse coming through on Sunday the 16th, with swell heights hitting 12 feet (E direction, 11-second period). The combined energy is massive at over 2600. That’s expert territory – way too big for the average punter – and the forecast even flags it as potentially too big for this break. If you’re a charger and you’re in, Sunday afternoon might be on with a gentle offshore wind, but it’s a serious step up.

After Monday the 17th, it drops off again. The rest of the second week is pretty lean with onshore winds and small, weak swells. The water temp is sitting at a warm 82°F, which is about a couple of degrees above normal for this time of year – lovely for a long session.

So, to sum it up: wait it out. The real sweet spot is Monday morning the 17th. Get on it.

Rusty.

Short Range Forecast

Heavy rain (total 80mm), heaviest during Tue night. Warm (max 27°C on Thu morning, min 23°C on Tue night). Winds decreasing (strong winds from the SSW on Tue night, light winds from the N by Wed night).

Days 5-7 Weather Summary

Light rain (total 9mm), mostly falling on Fri night. Warm (max 27°C on Fri afternoon, min 22°C on Sat night). Winds decreasing (fresh winds from the NNW on Sun morning, calm by Sun night).

Tue
11
Wednesday
12
Thursday
13
Friday
14
Saturday
15
Sunday
16
Monday
17
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
0
0
0
1
2
2
1
2
1
2
4
2
1
3
!
!
4
3
0
0
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
2.1
E
12
1.5
E
11
2.2
ESE
6
1.1
E
9
1.4
E
9
1.5
E
9
1.5
E
10
1.5
E
10
1.5
E
10
1.5
E
10
1.9
E
10
2.2
E
10
2.1
E
10
3
E
10
3.5
E
11
3.5
ENE
11
2.5
ENE
10
1.7
E
9
1.5
ENE
9
1.3
E
9
Wave Graph
Metric surfscale
Energy kJ
1229
514
383
201
320
375
426
434
434
424
646
913
821
1748
2469
2570
1314
452
307
269
Wind (km/h)
35
WSW
35
S
25
ESE
15
E
5
N
15
ENE
15
ENE
15
NE
20
NNE
20
ENE
15
NE
30
NNE
35
NE
30
N
35
NNW
15
NNW
10
WNW
5
S
20
SSW
20
SSW
Wind State
cross-on
on
cross-on
cross
off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
off
cross-off
off
cross-off
glassy
on
cross-on
High Tide
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
6:12AM1.40m
6:43PM1.39m
6:57AM1.29m
7:02PM1.40m
Low Tide
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
12:27PM0.38m
00:54AM0.46m
12:51PM0.53m
1:34AM0.43m
mod rain
heavy rain
thunderstorm
thunderstorm
thunderstorm
thunderstorm
clear
thunderstorm
thunderstorm
thunderstorm
thunderstorm
part cloud
part cloud
light rain
part cloud
part cloud
clear
clear
part cloud
part cloud
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
4:54
4:56
4:56
4:56
4:58
4:58
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:31
6:30
6:30
6:29
6:28
6:27
6:25
 mm
10
48
9
5
2
1
2
3
1
7
1
Temp °C
24
23
25
26
25
27
27
25
27
27
25
27
27
23
26
27
25
27
28
26
Feels °C
21
19
24
28
29
29
29
27
28
28
27
25
24
20
24
27
26
29
29
28
  • 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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