Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 am 30 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 30 Aug 2026:

  • Best quality surf: Tuesday 1 Sep, 3AM (local time) - 3ft (0.9m), 12s period, ESE swell with offshore winds.
  • Most powerful swell: Sunday 6 Sep, 3PM (local time) - 5ft (1.6m), 15s period, SSE swell with 1,035 kJ wave energy.
  • Next surfable swell (1★+): Sunday 30 Aug, 12PM (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 12PM. The primary swell is predicted to be 0.5m and 11s period with a secondary swell of 0.7m and 5s. 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 1.6m 15s and forecast to arrive on Sunday (Sep 06) 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 1.2m 5s period and expected on Friday (Sep 04) at 12PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+)12PM (Sun 30th Aug)1.5ft (0.5m) 11s
Best Surf 3AM (Tue 1st Sep)3ft (0.9m) 12s
Most Powerful 3PM (Sun 6th Sep)5ft (1.6m) 15s

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


The Lowdown

G’day, I’m Rusty. Let’s have a look at what’s on the table for Onjuku over the next couple of weeks. Mostly a slow start, but there’s a window of real promise later on, especially for the more experienced crew.

Right now, through Sunday the 30th and Monday the 31st of August, it’s pretty weak out there – surf around 2 to 1 ft from the east, with a short 11-second period pushing only moderate energy (104 to 204). Winds are a cross-off from the northeast, which keeps it clean, but there’s just not enough push to get excited about. The water is a touch warmer than normal at 82°, so it’s pleasant for a paddle, but the waves are poor.

Tuesday the 1st of September sees a small lift to 3 ft from the east-southeast, with period holding at 12 seconds and energy climbing into the moderate range (324). Still cross-off from the north-northeast, so the lines look clean – but it’s only marginal surf. Wednesday morning the 2nd is the first real glimmer: glassy conditions with the wind dropping to just 3 mph from the east-southeast, and the swell holds at 3 ft, 10-second period, with moderate energy (203). It’s a good call for a sneaky session if you’re keen, but crowds are possible at this spot.

We then hit a long, frustrating stretch. From Wednesday afternoon right through to Saturday the 6th, it’s mostly poor – onshore or cross-onshore winds, choppy conditions, and swell that’s either short-period junk or just messy. Thursday the 3rd and Friday the 4th are write-offs. Saturday the 5th has a bit more size at 5 ft from the east but with a terrible 6-second period and fresh cross-off winds – not doing anyone any favours.

Now, here’s where it gets interesting. Sunday the 6th of September brings a strong, long-period groundswell – 4 to 5 ft from the south, with a period of 12 to 15 seconds, and the energy jumps to very strong (1127 to 1278). The wind is a cross-off from the east-northeast, so the surf looks clean and the lines will have proper shape. That long-period swell will hold up well at Onjuku, especially as it’s an exposed beach setup, so expect longer lulls but some really good waves. This is the first standout window of the outlook.

Monday the 7th gets big – too big, really. Swell jumps to 10 to 12 ft from the east, with a short 9 to 10-second period, and energy goes through the roof (2688 to 4250). Winds are light cross-onshore, but this is only for experts – beginners shouldn’t even think about paddling out, it’s a heavy, powerful mess and might even be more interesting for kite-surfing than paddling.

Tuesday the 8th of September is the standout worth circling. Early morning brings offshore winds from the north at just 6 mph, and the swell drops to a still-chunky 8 ft from the east, 10-second period, with strong energy (2209). The conditions are clean and the waves will have plenty of push – excellent for experienced surfers. It’s the best on offer in the whole forecast, but remember crowds are possible here.

Wednesday the 9th and Thursday the 10th stay big but get messy – 6 to 10 ft from the south-southeast, with long 14-second periods and very strong energy (3161 to 3274), but cross-off winds are fresh to strong, keeping it clean but too big and raw for most. Friday the 11th is another whopper at 12 ft from the south, with strong breeze cross-off, and again only for the pros.

After that, the energy drops sharply from Saturday the 12th right through to Monday the 14th of September – poor conditions, onshore or strong cross-shore winds, and short-period slop. The window’s gone.

So, for the whole sixteen days, the real shine is on Tuesday the 8th of September – that 8 ft east swell with offshore northerly winds at Onjuku is the one to pencil in. Sunday the 6th also offers some nice longer-period groundswell in clean conditions, but the Tuesday morning session tops it all.

Rusty.

Short Range Forecast

Some drizzle, heaviest during Sun morning. Warm (max 27°C on Tue morning, min 23°C on Sun morning). Wind will be generally light.

Days 4-6 Weather Summary

Light rain (total 8mm), mostly falling on Wed night. Warm (max 29°C on Fri morning, min 22°C on Fri night). Winds increasing (calm on Wed morning, fresh winds from the SSW by Thu afternoon).

Sunday
30
Monday
31
Tuesday
1
Wednesday
2
Thursday
3
Friday
4
Saturday
5
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
1
1
0
0
1
2
1
2
2
0
0
0
0
0
0
1
1
1
0
1
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
0.4
SE
14
0.4
ESE
14
0.8
ESE
12
0.9
ESE
12
0.9
ESE
11
0.9
ESE
11
0.8
ESE
10
1.3
SE
6
0.7
ESE
11
1.4
SSE
6
1.4
SSE
6
1.2
SSE
6
1
SSE
6
0.9
SSE
6
0.8
SSE
6
0.9
ENE
6
0.6
SSE
16
1.2
SSE
15
Wave Graph
Metric surfscale
Energy kJ
59
60
57
57
73
175
237
214
170
116
118
133
161
149
115
82
64
47
57
208
666
Wind (km/h)
15
NNE
15
NNE
15
NNE
25
NE
25
NE
20
NNE
20
NNE
15
ENE
5
N
5
SE
20
S
20
SSW
20
SSW
30
SSW
30
SW
20
SW
5
NE
10
NW
25
NNE
30
NNE
30
NNE
Wind State
off
cross-off
off
cross-off
cross-off
cross-off
off
cross-off
glassy
glassy
on
on
cross-on
on
cross-on
cross-on
cross-off
cross-off
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
11:35AM0.32m
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
4:13AM0.36m
light rain
part cloud
part cloud
cloud
cloud
cloud
part cloud
part cloud
clear
clear
clear
thunderstorm
thunderstorm
clear
part cloud
part cloud
thunderstorm
cloud
cloud
light rain
mod 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
5:13
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:08
6:07
6:06
6:05
6:04
6:01
6:00
 mm
1
4
2
2
1
6
Temp °C
25
25
24
25
24
24
27
27
25
28
28
27
28
28
27
29
26
25
23
23
22
Feels °C
28
27
26
25
24
25
29
30
29
31
30
29
29
28
28
32
30
27
21
21
19
  • Map Icons:
  • Break
  • 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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