Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 pm 29 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
27.9°C
1.1° 

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


Onjuku surf forecast from 29 Aug 2026:

  • Best quality surf: Tuesday 1 Sep, 12AM (local time) - 2.5ft (0.8m), 12s period, ESE swell with cross-offshore winds.
  • Most powerful swell: Saturday 5 Sep, 9PM (local time) - 6ft (1.8m), 7s period, E swell with 302 kJ wave energy.
  • Next surfable swell (1★+): Saturday 29 Aug, 9PM (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 Saturday (Aug 29) at 9PM. The primary swell is predicted to be 0.5m and 11s period with a secondary swell of 0.4m and 11s. The wind is predicted to be offshore as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 1.8m 7s and forecast to arrive on Saturday (Sep 05) at 9PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.3m 6s period and expected on Saturday (Sep 05) at 3AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 9PM (Sat 29th Aug)1.5ft (0.5m) 11s
Best Surf12AM (Tue 1st Sep)2.5ft (0.8m) 12s
Most Powerful 9PM (Sat 5th Sep)6ft (1.8m) 7s

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


The Lowdown

Alright, Rusty here. Let’s have a look at what’s on the menu for Onjuku.

First off, water temps are sitting at 82°, which is a touch warmer than normal for this time of year – nothing crazy, just a nice little bonus for your session.

Right now, we’re in a bit of a flat spell to start. The first real action worth paddling out for isn’t until Tuesday morning, the 1st of September. That’s when we get a little bump of 3 ft from the ESE with a period of 12 seconds, combined energy sitting at 315 (moderate), and a light offshore breeze from the NNE. That’s clean, lined-up, and the sort of morning where you can get a few fun ones without too much fuss. Crowds are sometimes an issue here, so early is your friend.

Wednesday morning the 2nd keeps things rolling with 3 ft from the ESE, 10-second period, combined energy at 207 (moderate), and a light cross-offshore breeze from the NE. Still clean, still surfable, but nothing that’ll blow your mind.

After that, things get a bit messy. Thursday and Friday bring onshore winds, short period junk, and generally poor conditions. We’ve got a few days of pretty ordinary surf from the 3rd through the 5th, with small swell and wind that’s not doing us any favours.

Now, the standout window is from the 6th of September into the following week, but there’s a catch. On Sunday the 6th, we see 7 ft from the E at 8 seconds, combined energy hitting 966 (strong). That’s actually a decent size, but the short period means it’s going to be a bit lumpy and less organised. By Monday the 7th, we’re up to 8 ft from the ESE, but the wind is cross-onshore, so expect chop.

The real big stuff kicks in from the 8th of September. Swell builds to 10 ft from the ESE, period 12 seconds, combined energy shooting up to 3173 (very strong). That’s a serious groundswell. But here’s the thing – at 10 ft, this is expert-only territory. On Wednesday the 9th, we’ve got 12 ft from the ESE, period 12 seconds, combined energy 3225, and the wind is a clean cross-offshore from the E. That’s a beautiful combination if you’ve got the skill. But honestly, for most of us, it’s going to be too big and too powerful.

The week of the 10th to the 13th is dominated by huge swell (15 ft on the 10th, 12 ft on the 10th afternoon) and gale-force winds. That’s not a surf forecast – that’s a weather warning. Only the most experienced chargers should even be looking at the water then.

So, to wrap it up: the best bet for the average surfer is Tuesday morning the 1st of September. Clean, light offshore, moderate energy, and chest-high waves. If you’re an expert and you want a challenge, the 9th of September offers a clean, powerful, very big groundswell, but it’s not for the faint-hearted.

Rusty.

Short Range Forecast

Moderate rain (total 11mm), heaviest on Mon morning. Warm (max 27°C on Tue morning, min 21°C on Sat night). Wind will be generally light.

Days 5-7 Weather Summary

Moderate rain (total 12mm), heaviest on Thu night. Warm (max 28°C on Wed morning, min 23°C on Thu night). Wind will be generally light.

Sat
29
Sunday
30
Monday
31
Tuesday
1
Wednesday
2
Thursday
3
Friday
4
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
0
1
1
1
1
0
1
2
2
1
2
2
0
0
0
0
1
1
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)
0.5
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.4
ESE
14
0.8
ESE
12
0.9
ESE
12
0.9
ESE
11
0.9
ESE
11
0.8
ESE
10
1
ESE
7
1.1
SE
6
0.7
E
11
1.1
SSE
6
0.9
SSE
7
0.6
E
9
0.5
E
9
0.4
E
9
Wave Graph
Metric surfscale
Energy kJ
60
58
59
60
56
56
73
175
237
176
167
116
86
93
112
94
76
64
45
27
Wind (km/h)
10
ESE
20
NNW
20
N
10
NNE
10
N
15
ENE
20
ENE
15
NE
10
NNE
15
E
10
NE
15
NE
15
SSE
15
SSW
25
SSW
20
SW
10
NNW
15
NNE
20
NE
30
NE
Wind State
cross
off
off
cross-off
off
cross-off
cross-off
cross-off
cross-off
cross
cross-off
cross-off
on
on
cross-on
cross-on
cross-off
cross-off
cross-off
cross-off
High Tide
5:32PM1.40m
5:17AM1.43m
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
Low Tide
11:22PM0.53m
11:35AM0.32m
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
light rain
cloud
part cloud
part cloud
rain showers
mod rain
rain showers
part cloud
part cloud
clear
thunderstorm
part cloud
part cloud
thunderstorm
thunderstorm
cloud
thunderstorm
light rain
light rain
heavy rain
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:07
5:09
5:09
5:11
5:11
5:11
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:09
6:08
6:07
6:06
6:05
6:04
6:01
 mm
2
2
6
1
1
3
1
5
2
2
19
Temp °C
25
22
24
25
24
25
25
25
27
27
26
28
28
27
27
26
26
24
24
23
Feels °C
28
22
25
28
27
28
27
29
30
30
30
32
31
31
28
29
28
27
25
23
  • 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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