Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 am 26 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 26 Aug 2026:

  • Best quality surf: Thursday 27 Aug, 3PM (local time) - 2.5ft (0.7m), 13s period, E swell with offshore winds.
  • Most powerful swell: Wednesday 2 Sep, 6AM (local time) - 6.5ft (2.0m), 12s period, S swell with 1,198 kJ wave energy.
  • Next surfable swell (1★+): Thursday 27 Aug, 3PM (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 3PM. The primary swell is predicted to be 0.7m and 13s period with a secondary swell of 0.6m and 10s. The wind is predicted to be offshore as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 2.0m 12s and forecast to arrive on Wednesday (Sep 02) at 6AM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.2m 5s period and expected on Saturday (Aug 29) at 3PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 3PM (Thu 27th Aug)2.5ft (0.7m) 13s
Best Surf 3PM (Thu 27th Aug)2.5ft (0.7m) 13s
Most Powerful 6AM (Wed 2nd Sep)6.5ft (2.0m) 12s

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


The Lowdown

Alright folks, Rusty here. Let's take a good hard look at what's coming down the pipe for the next couple of weeks. We've got a bit of a slow start, some dodgy wind in the middle, but a proper wall of water is lining up for the brave souls out there.

Right now, we're in a flat spell. The water at Onjuku is sitting at a balmy 82°, which is a touch warmer than normal for this time of year, a nice little bonus. But the waves? Barely a ripple. We're looking at a frustratingly long stretch from Wednesday the 26th of August right through to about Saturday the 30th where there's just nothing doing. It's small, it's weak, with combined energy readings scraping the bottom of the barrel (346 on Wednesday morning), and the wind is mostly cross or onshore, making everything a choppy mess. It's a write-off for a paddle.

Finally, on Sunday the 30th, things get a little more interesting. We see a glimmer of hope with some clean conditions in the morning as a light N offshore blows. The swell is a timid 2 ft from the East, with a period of just 11 seconds, but the energy is low (98). It's surfable but ordinary. This sticks around through Monday the 31st as the swell nudges up to 2 ft from the NE with a shorter 7-second period. The wind stays offshore and light, but it's just not got any grunt. The energy is still weak (104). You could get wet, but don't expect much.

Then things get weird. On Tuesday the 1st of September, a new S swell starts to show up. By the afternoon, we get a massive jump in energy to 643 from a 3 ft S swell with a very long 16-second period. That's proper groundswell energy, but the wind is a cross-onshore from the SSE, making it choppy. That long period at a beach break like Onjuku can make waves close out and be hard to read. Wednesday the 2nd gets bigger, with 6 ft on offer in the morning and the energy climbing over 1000 (1029) – which is moderate to strong – but it's a direct onshore S wind at 9 mph. The afternoon is even worse with onshore wind and 7 ft swell. This whole window is a write-off for quality surf; it's big, messy, and onshore. Honestly, with that much wind and swell, the setup on Wednesday looks more interesting for kite surfing than paddle surfing.

The real story, and the standout of the entire outlook, is the weekend of the 6th and 7th of September. On Saturday the 6th, we get a proper monster. The combined energy rockets to 3895 on the morning – that's strong to very strong energy. We're looking at a solid 12 ft swell from the SSE with a 12-second period. The wind is a cross-shore from the ESE at 16 mph, which will create some texture but be rideable. However, be warned: at 12 ft, this is strictly for experts only. This is a big, powerful, dangerous wave. It is predicted to be too big for this break, so only the most experienced crew should even look at it. The crowd profile is listed as "sometimes" busy, so expect some local chargers out. The swell drops a touch to 10 ft in the afternoon, but the energy is still massive at 2793.

Sunday the 7th is still pumping, but the wind swings directly onshore from the S, which will ruin any quality. The swell is 8 to 8 ft with energy still over 2000, but with onshore wind and rain showers, it's going to be a washing machine. Don't bother. The following week trails off, with smaller, onshore windswell for Tuesday and Wednesday, and then it's back to flat, weak dribble.

So, to keep it simple: the absolute best on offer, and it's a proper call, is the morning of Saturday the 6th of September. Get on it if you have the skills and the guts. For everyone else, the little clean window on Sunday the 30th of August is your best bet for a gentle paddle.

Rusty.

Short Range Forecast

Heavy rain (total 22mm), heaviest during Thu morning. Warm (max 30°C on Wed morning, min 23°C on Thu afternoon). Mainly fresh winds.

Days 4-6 Weather Summary

Some drizzle, heaviest during Sat morning. Warm (max 26°C on Sat morning, min 24°C on Sat night). Wind will be generally light.

Wednesday
26
Thursday
27
Friday
28
Saturday
29
Sunday
30
Monday
31
Tuesday
1
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
2
0
0
0
1
0
0
1
1
1
1
1
0
1
1
1
2
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.9
SSE
10
0.9
SSE
9
0.8
SSE
9
0.7
SSE
10
0.7
E
13
0.7
E
13
0.7
E
12
0.6
E
12
0.6
E
12
0.6
E
12
0.5
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.5
E
11
0.7
NE
7
0.9
ENE
7
0.9
ENE
7
0.6
ESE
11
0.9
S
16
1.6
S
13
Wave Graph
Metric surfscale
Energy kJ
159
146
113
94
173
163
148
103
99
96
63
58
59
60
57
46
68
82
83
417
888
Wind (km/h)
15
WSW
30
SW
30
SW
10
W
20
NNE
15
SSW
20
WSW
20
WSW
10
NNE
20
ENE
25
ENE
10
NE
10
NNE
15
NE
15
N
10
N
5
E
5
E
5
ESE
15
SSE
10
SSE
Wind State
cross-on
cross-on
cross-on
cross
off
cross-on
cross-on
cross-on
off
cross-off
cross-off
cross-off
off
cross-off
off
off
cross
glassy
cross
cross-on
on
High Tide
4:41PM1.29m
3:17AM1.37m
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
Low Tide
9:42AM0.22m
9:51PM0.85m
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
clear
clear
rain showers
thunderstorm
cloud
light rain
thunderstorm
part cloud
rain showers
rain showers
part cloud
cloud
cloud
cloud
part cloud
part cloud
part cloud
part cloud
clear
part cloud
clear
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:05
5:05
5:07
5:07
5:07
5:09
5:09
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:14
6:13
6:12
6:09
6:08
6:07
6:06
 mm
2
12
3
2
3
1
Temp °C
30
29
27
27
24
26
28
27
26
26
26
25
25
24
24
26
26
25
28
28
27
Feels °C
31
30
29
31
25
28
29
28
29
25
25
25
28
26
26
30
30
29
31
30
31
  • 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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