Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 am 08 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
28.0°C
1.5° 

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


Onjuku surf forecast from 7 Sep 2026:

  • Best quality surf: Thursday 10 Sep, 12PM (local time) - 5.5ft (1.7m), 7s period, NE swell with offshore winds.
  • Most powerful swell: Tuesday 8 Sep, 6PM (local time) - 6ft (1.9m), 9s period, S swell with 614 kJ wave energy.
  • Next surfable swell (1★+): Thursday 10 Sep, 12PM (local time) - 5.5ft (1.7m), 7s period with NE 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 (Sep 10) at 12PM. The primary swell is predicted to be 1.7m and 7s period with a secondary swell of 1.2m and 8s. Another secondary swell of 0.3m and 15s 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 1.9m 9s and forecast to arrive on Tuesday (Sep 08) at 6PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.6m 6s period and expected on Wednesday (Sep 09) at 9PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+)12PM (Thu 10th Sep)5.5ft (1.7m) 7s
Best Surf12PM (Thu 10th Sep)5.5ft (1.7m) 7s
Most Powerful 6PM (Tue 8th Sep)6ft (1.9m) 9s

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


The Lowdown

Alright, Rusty here again, but this time I'm giving it to you in feet and miles per hour, the way the old-timers like it.

Well, the next couple of weeks at Onjuku are a real mixed bag, a proper rollercoaster. We've got a few moments that'll get your heart pumping, but you gotta be patient.

The first few days are a total washout. Tuesday and Wednesday (8th and 9th), we're looking at a choppy 5 to 7 foot south swell, but the wind is howling from the southwest, just ruining it. The water's a balmy 82°, a touch warmer than normal, but that's the only good thing. The wave energy is moderate, and it's just not worth your time.

Thursday the 10th, things start to look a little cleaner. The swell drops to 5-6 feet from the northeast, and the wind goes offshore from the north. That's a clean look, but the period is a short 7 seconds, so it's a bit weak. Wave energy is moderate. It's marginal, but there's a window.

Friday the 11th, that's the first real standout. In the morning, a smaller 3-foot swell from the east-northeast, clean. The real treat is the afternoon. The swell drops to 2 feet, but the period jumps to 14 seconds. That's proper groundswell, coming from the east. The wind goes light offshore, making it glassy. The wave energy is moderate, but for a small, clean, long-period swell, this is a classic Onjuku moment. It'll be lined up and fun on a longboard. Just remember, this break is inconsistent, so you gotta be patient.

The weekend from the 12th to the 14th is a bit of a lull. The swell stays small, around 2 feet, with that long period from the east, but the wind is mostly cross-off or light onshore. It's clean, but it's tiny. Good for a beginner, but not much else.

We hit a flat spell from the 15th through the 20th. The wind is all over the place, mostly onshore or strong, and the swell is tiny or messy. Not worth it.

Now, hold on, because the 21st and 22nd are where it gets serious, and dangerous. Monday the 21st, we're looking at a massive 7 to 8 foot swell from the south-southeast with a massive 16-second period. The wave energy is through the roof, over 5,000. This is a big, powerful groundswell. The wind is howling offshore on Monday morning, but it's a near-gale, so you'll be fighting it just to get out. Experts only. By Tuesday the 22nd, the swell is predicted to be *too big* for Onjuku, hitting 11 feet with a 13-second period and energy near 6,000. The wind looks good in the morning, but the size is just too much for this spot. This is big wave territory.

Finally, Wednesday the 23rd, we get the real payoff. The swell is still a solid 10 feet from the east-northeast, with a 15-second period. The wave energy is still very strong (over 3,500). The wind is gentle offshore from the north in the morning, making for absolute perfection. This is the best of the entire forecast. It's a big, clean, powerful groundswell with light offshore winds. It's "excellent conditions for experienced surfers," and I'm not arguing. This is a standout day for the crew who can handle it, but at 10 feet, it's way too big for beginners.

So, to wrap it up: Friday the 11th is your best bet for a clean, small-wave session. But if you're a seasoned surfer looking for some serious power, circle Wednesday the 23rd on your calendar. That's the one.

Rusty.

Short Range Forecast

Moderate rain (total 14mm), heaviest on Wed night. Warm (max 29°C on Wed morning, min 19°C on Thu night). Winds decreasing (strong winds from the SSW on Tue night, light winds from the N by Thu night).

Days 4-6 Weather Summary

Light rain (total 8mm), mostly falling on Fri morning. Warm (max 25°C on Sun afternoon, min 20°C on Fri morning). Wind will be generally light.

Tuesday
8
Wednesday
9
Thursday
10
Friday
11
Saturday
12
Sunday
13
Monday
14
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
0
0
1
1
2
2
2
2
2
1
1
0
1
2
2
1
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)
1.7
S
9
1.6
S
9
1.7
S
9
2.1
S
8
2
S
8
1.4
S
8
1.8
NE
7
1.6
NE
7
1.3
ENE
7
1
ENE
8
0.5
E
14
0.5
E
14
0.6
E
14
0.6
E
13
0.6
E
13
0.6
E
13
0.9
SE
9
0.9
SE
9
1.1
SE
9
1.1
SE
9
1.1
SE
9
Wave Graph
Metric surfscale
Energy kJ
473
404
419
558
546
278
289
246
183
117
101
97
134
128
128
123
125
118
225
216
197
Wind (km/h)
20
SW
20
SSW
30
SSW
35
SW
35
SW
30
NE
30
NNE
30
N
20
N
15
NNE
15
NNE
15
NNE
15
NE
20
NE
20
NNE
20
NNE
15
ENE
5
ENE
5
SSE
10
S
10
S
Wind State
cross-on
cross-on
cross-on
cross-on
cross-on
cross-off
cross-off
off
off
cross-off
off
off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-on
on
on
High Tide
3:57PM1.30m
2:06AM1.33m
4:14PM1.34m
3:06AM1.40m
4:32PM1.36m
3:56AM1.45m
4:50PM1.39m
4:41AM1.47m
5:08PM1.41m
5:24AM1.44m
5:26PM1.43m
6:04AM1.38m
5:44PM1.44m
Low Tide
8:59PM0.95m
9:17AM0.17m
9:34PM0.80m
9:55AM0.18m
10:07PM0.64m
10:29AM0.24m
10:40PM0.50m
10:59AM0.34m
11:13PM0.38m
11:26AM0.45m
11:46PM0.30m
11:50AM0.57m
00:19AM0.26m
part cloud
part cloud
thunderstorm
clear
thunderstorm
mod rain
light rain
cloud
cloud
mod rain
cloud
cloud
cloud
cloud
cloud
part cloud
part cloud
part cloud
clear
clear
clear
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:15
5:16
5:16
5:16
5:18
5:18
5:18
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
5:57
5:54
5:53
5:52
5:51
5:49
5:47
 mm
3
1
9
1
8
Temp °C
28
28
27
29
28
22
20
20
20
20
21
21
22
23
22
24
25
24
26
26
26
Feels °C
30
30
28
28
28
21
17
17
18
21
22
22
23
23
23
26
27
27
30
29
30
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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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