Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 am 12 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
26.5°C
0.3° 

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


Onjuku surf forecast from 11 Sep 2026:

  • Best quality surf: Saturday 12 Sep, 12PM (local time) - 2ft (0.6m), 14s period, E swell with offshore winds.
  • Most powerful swell: Saturday 19 Sep, 9AM (local time) - 8ft (2.5m), 15s period, SE swell with 3,109 kJ wave energy.
  • Next surfable swell (1★+): Saturday 12 Sep, 12PM (local time) - 2ft (0.6m), 14s 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 (Sep 12) at 12PM. The primary swell is predicted to be 0.6m and 14s period with a secondary swell of 0.5m and 9s. Another secondary swell of 0.6m and 6s is also forecast. The wind is predicted to be offshore as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 2.5m 15s and forecast to arrive on Saturday (Sep 19) at 9AM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.4m 6s period and expected on Thursday (Sep 17) at 6AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+)12PM (Sat 12th Sep)2ft (0.6m) 14s
Best Surf12PM (Sat 12th Sep)2ft (0.6m) 14s
Most Powerful 9AM (Sat 19th Sep)8ft (2.5m) 15s

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


The Lowdown

Alright, let's get into it.

To be straight with you, the next couple of days are pretty quiet. The swell is small, just ankle to knee-high, and while the wind is okay, the conditions aren't really doing us any favors. It’s going to be a bit of a flat, ordinary start to the outlook.

We’re looking at the weekend, and it’s still fairly slow. Saturday is clean but small, with about 1ft of east swell pushing through at a long 14-second period. The light offshore wind will have the surface looking nice, but there just isn't enough power to get excited about. Sunday sees a slight bump to 3ft, still from the east-southeast, and with light offshore winds in the morning, it will be the pick of the early days. It’s surfable, but you won’t be telling your mates about it.

Then we hit a bit of a lull. Monday and Tuesday get chopped up with onshore winds and the swell gets messy. It’s going to be poor to marginal, so don’t get your hopes up. There’s a window early Tuesday with a tiny 2ft east swell and glassy conditions before the wind turns onshore, but it’s fleeting.

The real story starts to build towards the end of next week. The swell starts to pick up significantly. By Friday the 18th, we’re looking at 8ft of east-northeast swell, but the wind will be ripping at 25 mph, making it a complete mess. Not good. The energy is there, but you can’t surf that.

Now, let's talk about the standout. The period from Saturday the 19th through Monday the 21st is where it’s at. There’s a big, powerful groundswell from the southeast that arrives. Saturday the 19th sees 8ft to 10ft of SE swell, and the energy readings are through the roof. The wind is cross-offshore and light, which is good, but it’s big. This is expert territory for sure.

But the real gem for me is Sunday morning, the 20th. We’ve got a solid 8ft of southeast swell, and the wind is light and cross-offshore. The energy is still very strong, and the conditions are looking clean. This is the big day for the experienced crew. It’s powerful and pushing, a proper challenge.

Onjuku will be handling this swell, and with that southeast direction, it’s right in its wheelhouse. This is a day for the confident surfer; the power is real. The water is a warm 80°, which is about normal for this time of year, so it’s all about the waves. Be aware, the place can get busy when it's good, so expect some company out there.

Monday the 21st eases off a touch to 5-6ft, but it’s still a solid south-southeast swell with clean, offshore winds in the morning. Another really good day, just a step down in size from the day before.

After that, the swell fades out quickly, and we get a windy, blown-out mess on the 23rd before it drops right off again. The last days of the forecast look small and unremarkable. We finish where we started, with knee-high waves and a bit of chop.

So, in short: the early part is a write-off, get through the working week, and be ready for that big, powerful SE groundswell this weekend – that’s the one.

Rusty.

Short Range Forecast

Light rain (total 5mm), mostly falling on Mon night. Warm (max 27°C on Mon morning, min 22°C on Sat morning). Wind will be generally light.

Days 4-6 Weather Summary

Light rain (total 2mm), mostly falling on Wed night. Warm (max 26°C on Tue morning, min 22°C on Wed night). Winds increasing (calm on Tue morning, strong winds from the NNE by Thu night).

Saturday
12
Sunday
13
Monday
14
Tuesday
15
Wednesday
16
Thursday
17
Friday
18
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
2
2
1
0
0
0
0
2
0
2
1
1
1
0
0
1
0
0
3
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.6
E
14
0.6
E
13
0.7
ESE
13
0.9
ESE
13
0.7
ESE
13
0.6
E
12
0.9
SE
9
1.1
SE
9
1.1
SE
9
0.7
E
14
0.8
E
14
0.7
E
13
0.9
E
13
0.8
E
12
0.7
E
12
1.6
NE
6
1.9
NE
7
2.4
ENE
8
2.4
ENE
8
2.3
ENE
8
1.1
SE
16
Wave Graph
Metric surfscale
Energy kJ
134
128
184
242
178
108
129
220
202
195
261
167
273
193
138
195
352
770
770
696
694
Wind (km/h)
15
NNE
20
NNE
15
NNE
10
NNE
10
S
15
S
20
SSW
20
SSW
15
SSW
5
SSW
15
SSW
5
NNW
15
NE
20
NE
20
N
30
NNE
35
NE
35
NNE
40
NNE
40
NNE
20
NE
Wind State
cross-off
off
off
off
on
on
cross-on
on
cross-on
glassy
on
glassy
cross-off
cross-off
off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
High Tide
5:08PM1.41m
5:24AM1.44m
5:26PM1.43m
6:04AM1.38m
5:44PM1.44m
6:45AM1.29m
6:03PM1.43m
7:26AM1.19m
6:22PM1.41m
8:14AM1.09m
6:42PM1.37m
9:27AM0.99m
7:03PM1.31m
Low Tide
10:59AM0.34m
11:13PM0.38m
11:26AM0.45m
11:46PM0.30m
11:50AM0.57m
00:19AM0.26m
12:11PM0.69m
00:53AM0.27m
12:28PM0.79m
1:31AM0.32m
12:40PM0.87m
2:15AM0.40m
12:34PM0.94m
light rain
cloud
part cloud
part cloud
part cloud
clear
clear
part cloud
light rain
part cloud
part cloud
part cloud
cloud
cloud
light rain
light rain
cloud
part cloud
light rain
light rain
rain showers
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:18
5:18
5:18
5:20
5:20
5:22
5:22
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
5:51
5:49
5:47
5:46
5:45
5:44
5:42
 mm
2
3
1
1
5
2
8
Temp °C
22
22
23
25
25
26
27
27
26
26
26
26
24
23
22
23
23
23
22
23
24
Feels °C
23
23
25
29
28
30
29
29
29
28
28
30
26
24
23
22
20
20
19
22
25
  • 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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