Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 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, 3AM (local time) - 3ft (0.9m), 12s period, ESE swell with cross-offshore winds.
  • Most powerful swell: Sunday 6 Sep, 12AM (local time) - 6ft (1.8m), 7s period, ENE swell with 337 kJ wave energy.
  • Next surfable swell (1★+): Sunday 30 Aug, 6AM (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 6AM. The primary swell is predicted to be 0.5m and 11s period with a secondary swell of 0.4m and 7s. 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 Sunday (Sep 06) at 12AM. 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 5s period and expected on Friday (Sep 04) at 3AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 6AM (Sun 30th Aug)1.5ft (0.5m) 11s
Best Surf 3AM (Tue 1st Sep)3ft (0.9m) 12s
Most Powerful12AM (Sun 6th Sep)6ft (1.8m) 7s

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


The Lowdown

Alright, mates, let’s break it down. The surf around here is pretty quiet at first, but there’s a big window of solid waves coming if you know what you’re doing.

Onjuku (Chiba) is the only spot worth talking about. The first few days are dead—Sunday the 30th and Monday the 31st have tiny, weak swell with clean but useless conditions.

Things improve Tuesday morning, September 1st. You’ll see clean 3ft ESE swell with a 12-second period and moderate energy (315). The wind is light and cross-off, so the waves will be clean. It’s inconsistent here, so you’ll wait for sets. Wednesday morning the 2nd is similar: 3ft, 10-second ESE swell with clean conditions and a light breeze. Fun little waves.

Then Thursday and Friday are messy with onshore wind and chop. Not worth it.

The real show starts Sunday, September 6th. Swell jumps to 6ft from the east with 8-second period. Combined energy is strong (562), and the wind stays clean and cross-off. The short period means it’ll be a bit fat and weak at the beach, but a point or reef could work. Monday the 7th holds similar.

The standout stretch begins Tuesday, September 8th. Morning sees 8ft SE swell with a 10-second period and massive energy (1309)—this is big, powerful groundswell. Wind is light and cross-off, so the surf will be clean and lined up. But at over 8ft, this is experts-only. Beginners stay on the beach. The swell direction (SE) is a perfect match for the optimum SSE.

Wednesday the 9th still has 7ft to 8ft swell and strong energy, but the wind picks up—fresh to moderate cross-off—so it stays clean but gets harder. Thursday the 10th is another standout: 8ft SE swell with a 12-second period, very long period groundswell. The combined energy is a huge 2044. Wind is strong offshore from the NNE at 28 mph, making for clean, hollow waves—but paddling in will be brutal. For the hardcore only.

Friday the 11th gets messy with strong cross-shore winds and lumpy conditions. The weekend is blown out by near gale onshore slop.

Finally, Monday, September 14th offers a nice change: 4ft SSW swell with a 13-second period, moderate energy (614), and clean cross-off winds. The swell is from the SSW, not the optimum SSE, but it’s long-period and will offer good shape. Much more manageable for intermediates.

Best on offer: Tuesday, September 8th morning is the clear winner—big, clean, powerful SE groundswell with light winds. Thursday, September 10th morning is the other standout for the brave and strong paddlers with that strong offshore wind.

- Rusty

Short Range Forecast

Light rain (total 5mm), mostly falling on Sat night. Warm (max 27°C on Tue morning, min 22°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 afternoon, min 22°C on Thu night). Winds increasing (light winds from the NE on Wed morning, fresh winds from the ENE by Thu night).

Sunday
30
Monday
31
Tuesday
1
Wednesday
2
Thursday
3
Friday
4
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
0
0
1
0
1
1
2
1
2
2
0
0
0
0
0
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
0.5
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
0.8
ESE
10
0.8
ESE
12
0.7
E
11
0.6
E
10
1.2
S
6
1.3
ENE
6
1.1
ENE
7
1.5
ENE
6
Wave Graph
Metric surfscale
Energy kJ
58
59
60
56
56
73
175
237
173
183
118
111
192
116
78
108
115
107
160
Wind (km/h)
25
NNW
20
NNE
15
NE
10
NNE
15
NE
15
ENE
15
NE
15
NE
15
ENE
10
NNE
10
NE
15
S
20
SSW
20
SSW
20
SSW
30
ENE
15
NE
20
ENE
25
NE
Wind State
off
cross-off
cross-off
off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
on
on
cross-on
cross-on
cross-off
cross-off
cross-off
cross-off
High Tide
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
part cloud
part cloud
light rain
rain showers
rain showers
part cloud
part cloud
clear
part cloud
part cloud
part cloud
thunderstorm
light rain
thunderstorm
mod rain
cloud
cloud
part cloud
<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
1
1
2
1
2
1
1
8
Temp °C
23
25
25
25
26
26
25
27
27
25
27
28
27
26
28
23
24
25
24
Feels °C
25
26
27
28
28
28
27
30
30
29
31
31
30
29
30
22
25
24
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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