Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 pm 11 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, 9AM (local time) - 2ft (0.6m), 14s period, E swell with offshore winds.
  • Most powerful swell: Friday 18 Sep, 9PM (local time) - 10ft (3.0m), 15s period, SE swell with 3,686 kJ wave energy.
  • Next surfable swell (1★+): Saturday 12 Sep, 9AM (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 9AM. The primary swell is predicted to be 0.6m and 14s period with a secondary swell of 0.5m 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 3.0m 15s and forecast to arrive on Friday (Sep 18) at 9PM. 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 9AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 9AM (Sat 12th Sep)2ft (0.6m) 14s
Best Surf 9AM (Sat 12th Sep)2ft (0.6m) 14s
Most Powerful 9PM (Fri 18th Sep)10ft (3.0m) 15s

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


The Lowdown

G’day, Rusty here, and I’ve got the scoop on what’s coming up for the next couple of weeks. It’s a bit of a slow start, but there’s some real pulse in the water if you’re willing to wait. The first decent surf doesn’t show until Saturday the 12th, and from there we’re looking at a patchy run with a few standout windows. Let’s get into it.

We kick off on Saturday the 12th of September at Onjuku. Small but clean – we’re looking at 2 ft of easterly swell, with a period of 14 seconds, giving it some long-period groundswell feel. The wind is offshore from the NNE at 12 mph, keeping it glassy. The combined swell energy is sitting at 202, which is moderate. It’s inconsistent here, so you’ll be waiting between sets, but when they come, the shape will be there. Water temp is about average for the time of year, no major anomaly to report. Crowds are sometimes around, so you might have a few mates in the water.

Sunday the 13th is similar – 2 ft from the ESE, still with that clean vibe in the morning. Light offshore winds from the north at 6 mph, and the energy bumps up to 218. Afternoon gets a bit sketchy with an onshore crosswind, so aim for the early session. Monday the 14th is a write-off – onshore winds and messy surf, better to take the day off. Tuesday the 15th has a gem of a morning: glassy conditions, light SSW winds at 3 mph, and 2 ft of easterly swell with a 14-second period. The energy jumps to 377, which is a sign of life. It’s still inconsistent, but those glassy windows are precious.

Wednesday the 16th and Thursday the 17th are marginal at best – small waves and choppy or cross-off winds. Not worth rushing out for.

Now, Friday the 18th gets interesting. We’ve got a pulse of 6 ft from the SE early, with a very long 17-second period. The combined energy skyrockets to 2018 – that’s strong stuff. Wind is offshore from the NNE at 22 mph, so it’ll be clean but fresh. This is definitely one for experienced surfers; at that size and period, it’s going to be powerful and a bit heavy. Chances are the crowd will thin out because it’s a handful. Later in the day it builds to 7 ft, still with a 16-second period and energy at 2887. This is the standout in the first week – big, clean, and for those who can handle it.

Saturday the 19th sees the swell pushing 10 ft, but the wind turns cross-off, and it’s a bit too large for Onjuku’s setup. The energy is massive at 3423, but it’s really only for experts at this size. Sunday the 20th drops back to 5 ft from the SSE, with clean cross-off winds and energy at 894. This is a solid option – moderate size and clean, though still on the bigger side for beginners.

The second week is a real rollercoaster. Monday the 21st is small and clean-ish at 4 ft, but by Tuesday the 22nd the wind goes onshore and ruins it. Wednesday the 23rd is huge but blown out – 5 ft with a 15-second period but near-gale SSW winds at 34 mph. That’s a no-go for surfing, unless you’ve got a kite. Thursday the 24th cleans up with cross-off winds and a double overhead swell at 10 ft, energy at 4762 – that’s for the brave only. Friday the 25th pushes 12 ft, and the report is clear: too big for this break. Same for Saturday the 26th at 15 ft, and Sunday the 27th at 13 ft. These are massive, clean, cross-off days, but only for big wave chargers who know the spot well.

Best on offer: the early clean windows on Saturday the 12th and Tuesday the 15th morning for small-wave fun, and the big, powerful pulse on Friday the 18th for the experienced crew. The last week is pure size – keep an eye on it, but don’t expect a normal paddle.

Stay safe, check the tides, and I’ll catch you in the water.

Rusty

Short Range Forecast

Light rain (total 3mm), mostly falling on Fri night. Warm (max 27°C on Mon morning, min 21°C on Fri night). Wind will be generally light.

Days 5-7 Weather Summary

Moderate rain (total 10mm), heaviest on Mon night. Warm (max 26°C on Mon night, min 22°C on Wed night). Winds increasing (calm on Tue afternoon, fresh winds from the NNE by Thu afternoon).

Saturday
12
Sunday
13
Monday
14
Tuesday
15
Wednesday
16
Thursday
17
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
2
2
2
2
1
0
0
0
1
2
1
2
1
1
1
1
0
2
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.6
E
14
0.6
E
14
0.6
E
13
0.7
ESE
13
0.7
ESE
13
0.7
E
13
0.6
E
12
0.9
SE
9
1.1
SE
9
1.2
SE
9
0.7
E
14
0.8
E
14
1.1
SE
9
0.8
E
13
0.8
E
12
0.7
E
12
0.5
E
12
1.7
NE
6
0.6
SE
21
Wave Graph
Metric surfscale
Energy kJ
136
134
128
184
176
168
108
115
217
225
192
257
174
215
193
138
67
230
358
Wind (km/h)
15
NNE
20
NNE
20
NNE
15
N
10
N
5
E
5
SSE
15
SSW
20
SSW
15
WSW
5
SSW
10
S
10
NNE
15
NNE
20
NE
15
NNE
20
NNE
30
NNE
30
NNE
Wind State
cross-off
off
off
off
off
cross
on
on
cross-on
cross
glassy
on
off
cross-off
cross-off
cross-off
off
cross-off
off
High Tide
4:41AM1.47m
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
Low Tide
10:40PM0.50m
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
light rain
light rain
cloud
cloud
part cloud
part cloud
clear
clear
part cloud
light rain
rain showers
part cloud
cloud
light rain
cloud
light rain
light rain
cloud
light rain
<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
<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
 mm
1
2
2
1
1
4
2
1
Temp °C
21
22
22
22
24
25
26
27
27
26
26
26
25
23
23
23
22
22
22
Feels °C
22
23
23
24
28
29
30
30
29
29
29
29
29
25
24
25
22
20
20
  • 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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