Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 am 27 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
28.0°C
1.2° 

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


Onjuku surf forecast from 27 Aug 2026:

  • Best quality surf: Thursday 27 Aug, 6PM (local time) - 2.5ft (0.7m), 13s period, E swell with cross-offshore winds.
  • Most powerful swell: Thursday 3 Sep, 3AM (local time) - 5ft (1.6m), 11s period, S swell with 595 kJ wave energy.
  • Next surfable swell (1★+): Thursday 27 Aug, 6PM (local time) - 2.5ft (0.7m), 13s 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 Thursday (Aug 27) at 6PM. The primary swell is predicted to be 0.7m and 13s period with a secondary swell of 1.0m and 6s. Another secondary swell of 1.4m and 6s is also forecast. 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 11s and forecast to arrive on Thursday (Sep 03) at 3AM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 5s period and expected on Saturday (Aug 29) at 3PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 6PM (Thu 27th Aug)2.5ft (0.7m) 13s
Best Surf 6PM (Thu 27th Aug)2.5ft (0.7m) 13s
Most Powerful 3AM (Thu 3rd Sep)5ft (1.6m) 11s

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


The Lowdown

Alright, Rusty here, let’s talk about what’s in store for Onjuku.

Right off the bat, the next week and a half is looking pretty grim for a proper session. We’ve got a long stretch of poor surf and dodgy conditions, with the first real glimmer of hope not showing up until September 6th. The water is a touch warmer than normal for this time of year, sitting at 82°, but that’s about the only nice thing going on for a while.

Thursday August 27th is a write-off. We’ve got a messy 4 ft SW windswell with a short 6-second period, cross-on wind, and a risk of thunderstorms. The energy is weak (307) and the surf is poor. It doesn’t get any better through the afternoon. Friday the 28th is barely surfable, with a marginal 2 ft from the east and a long 12-second period, but the cross-shore wind and questionable conditions keep it a no-go. Saturday the 29th sees tiny 2 ft to 2 ft east swell, but the wind is clean with a cross-offshore breeze – still, the wave energy is very low (136 and 129), so it’s not worth getting wet.

Sunday August 30th morning is the first bit of relief. The swell is still tiny at 2 ft from the east, but the wind is *glass* – dead calm. The water is glassy, but the wave energy is pitiful (92). It’s a paddle-around kind of day, not a surf day. The rest of that week stays flat and poor, with onshore winds continuing to wreck any chance of a wave.

We finally get a pulse of proper swell on Saturday September 5th morning. A 7 ft east swell rolls in, but it’s a short-period 7-second windswell with a fresh cross-offshore breeze. The energy is up to 519, which is moderate, but the conditions are still marginal. The wind is clean, but that short period makes it fat and lumpy. This one is for the bigger boards only.

Now, the standout. Sunday September 6th is the day to circle. The morning brings a solid 8 ft east-southeast swell (876 energy) with a gentle offshore wind from the north. The period is 9 seconds, giving it some shape. Conditions are clean and lined up. This is the best on offer in the whole 16-day window. The afternoon drops to 5 ft, but it’s still clean. If you’re an experienced surfer, get on it. That 8 ft is pushing into expert territory, but with offshore wind, it’ll be worth it.

Monday September 7th is still decent, with 5 ft from the south and clean cross-offshore wind, though the quality drops a notch. Tuesday the 8th is smaller but clean, with 3 ft from the south and a long 11-second period. The energy is moderate (287). It’s a good backup day.

There’s a bit of a gap again after that, but Friday September 11th morning is another very good call. The swell is 4 ft from the south-southwest with a very long 14-second period, and the wind is glassy. The energy is strong (779). This is a groundswell, so it’ll be lined up and powerful. The afternoon sees a bump to 8 ft, but the period drops to 7 seconds, so the morning is the pick.

Overall, the first week is a bust. The real action is from September 6th to 11th. Sunday the 6th morning is the absolute standout, with Friday the 11th morning a close second. Keep your eyes on those windows.

- Rusty

Short Range Forecast

Moderate rain (total 16mm), heaviest on Thu morning. Warm (max 29°C on Thu morning, min 24°C on Thu afternoon). Wind will be generally light.

Days 4-6 Weather Summary

Light rain (total 6mm), mostly falling on Tue night. Warm (max 27°C on Sun afternoon, min 24°C on Mon night). Wind will be generally light.

Thursday
27
Friday
28
Saturday
29
Sunday
30
Monday
31
Tuesday
1
Wednesday
2
AM
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
1
0
0
0
1
1
0
0
1
2
1
1
1
0
0
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)
0.8
SSE
10
0.7
E
13
0.7
E
13
1.6
SW
6
0.9
SSW
8
0.6
E
12
0.6
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.7
S
10
0.8
S
11
0.9
ESE
11
0.9
ESE
11
1.1
E
11
1
E
11
1.1
S
10
1.1
S
11
Wave Graph
Metric surfscale
Energy kJ
120
173
163
172
109
99
94
60
58
59
61
56
57
98
155
176
205
287
233
262
267
Wind (km/h)
20
WSW
25
WSW
15
SW
15
W
10
SSE
15
E
20
E
15
E
10
ENE
5
NNE
10
SSW
10
WSW
5
NE
10
ENE
15
NE
20
NE
20
E
15
SE
20
S
30
S
35
SSW
Wind State
cross-on
cross-on
cross-on
cross
cross-on
cross
cross
cross
cross-off
cross-off
cross-on
cross-on
cross-off
cross-off
cross-off
cross-off
cross-off
cross-on
on
on
on
High Tide
4:57PM1.33m
3:58AM1.42m
5:14PM1.37m
4:38AM1.44m
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
Low Tide
10:12AM0.19m
10:21PM0.74m
10:41AM0.20m
10:51PM0.63m
11:09AM0.24m
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
thunderstorm
thunderstorm
light rain
thunderstorm
part cloud
part cloud
part cloud
cloud
part cloud
cloud
part cloud
part cloud
thunderstorm
part cloud
part cloud
part cloud
part cloud
thunderstorm
clear
thunderstorm
clear
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:05
5:07
5:07
5:07
5:09
5:09
5:11
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:13
6:12
6:09
6:08
6:07
6:06
6:05
 mm
7
5
2
2
1
5
2
Temp °C
29
28
26
27
28
26
27
26
25
26
27
26
26
26
25
26
26
26
28
28
27
Feels °C
32
30
27
31
32
29
27
27
28
31
31
30
31
30
27
28
27
29
29
28
27
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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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