Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 am 09 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
27.9°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 9 Sep 2026:

  • Best quality surf: Friday 11 Sep, 12AM (local time) - 4.5ft (1.3m), 7s period, ENE swell with offshore winds.
  • Most powerful swell: Wednesday 9 Sep, 6PM (local time) - 8ft (2.5m), 9s period, SSW swell with 1,070 kJ wave energy.
  • Next surfable swell (1★+): Friday 11 Sep, 12AM (local time) - 4.5ft (1.3m), 7s period with ENE 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 Friday (Sep 11) at 12AM. The primary swell is predicted to be 1.3m and 7s period with a secondary swell of 0.8m and 8s. Another secondary swell of 0.4m and 14s 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 9s and forecast to arrive on Wednesday (Sep 09) at 6PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.0m 5s period and expected on Friday (Sep 11) at 9PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+)12AM (Fri 11th Sep)4.5ft (1.3m) 7s
Best Surf12AM (Fri 11th Sep)4.5ft (1.3m) 7s
Most Powerful 6PM (Wed 9th Sep)8ft (2.5m) 9s

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


The Lowdown

G’day, Rusty here, looking at the next stretch of surf for Onjuku.

Right off the bat, we’ve got a bit of a dud on our hands. The first few days are a write-off. Wednesday is a total mess with strong cross-onshore wind and lumpy, dangerous conditions. Thursday cleans up a bit with a fresh offshore wind, but the swell is short-period and not offering much quality. Honestly, the best we can say for the first few days is that Friday morning (11th September) might give you a tiny window. We’ve got a clean, moderate offshore wind and a tiny 2ft swell running on a very long 14-second period. The energy is weak (226), so it’s more of a longboard cruise than anything with punch. The water is a touch warmer than normal at 82°.

Now, if you can wait, the real standout is shaping up. Mark your calendar for Tuesday morning, the 22nd of September. That’s the pick of the whole period. We’re looking at a glassy, dead-calm surface with a 3ft swell from the south, and that groundswell has a beautiful 14-second period. The combined energy is moderate (544), and the cross-off wind on the 24th might clean things up further, but the 22nd morning is the moment. The south swell direction isn’t a perfect match for the optimum SSE, but with glassy conditions, it’s hard to complain. The break is exposed and inconsistent, so don’t expect a constant wave train, but when the sets come through, they’ll be clean and well-shaped.

For the rest of the second week, the swell picks up a bit more, but the wind turns against us. The 23rd and 24th have a very long-period swell (16-seconds) pushing in, with moderate to strong energy (1016-1534), but it’s mostly cross-onshore, so it’ll be choppy and messy. The 24th morning has a fresh offshore wind, so that might be a salvageable session, but the swell is a bit much for beginners at 5ft. For the experts, though, with that long period and a cross-off wind, it could be a solid day.

A note on the 21st: the swell is pushing 6ft from the ENE with a short 8-second period and cross-on wind. That’s a messy, chunky setup that’s more interesting for the kite surfers than paddle surfers.

Overall, the first week is a struggle. The blank run from Wednesday through to Friday is mostly a no-go. The real standout is the 22nd morning. After that, the 24th morning is a promising but less certain call for the crew who can handle bigger, cleaner lines.

Rusty.

Short Range Forecast

Heavy rain (total 38mm), heaviest during Wed night. Warm (max 29°C on Wed morning, min 19°C on Thu morning). Mainly strong winds.

Days 4-6 Weather Summary

Light rain (total 5mm), mostly falling on Sat morning. Warm (max 26°C on Mon morning, min 22°C on Sat morning). Wind will be generally light.

Wednesday
9
Thursday
10
Friday
11
Saturday
12
Sunday
13
Monday
14
Tuesday
15
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
2
1
0
2
2
0
1
1
1
2
2
1
2
0
0
0
0
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)
2.5
S
8
2.4
S
9
1.6
S
9
1.7
NE
7
1.5
NE
7
1.3
ENE
7
0.5
E
14
0.5
E
14
0.6
E
14
0.6
E
14
0.6
E
13
0.6
ESE
13
0.6
E
13
0.9
SE
9
0.9
SE
9
1.2
SE
9
1.1
SE
9
0.8
E
14
1.2
ESE
9
0.7
E
14
0.8
E
13
Wave Graph
Metric surfscale
Energy kJ
850
861
380
263
204
183
106
101
136
134
128
139
123
125
120
230
194
239
197
200
222
Wind (km/h)
40
SW
35
SW
30
NNE
30
NNE
25
NNE
20
NNE
20
N
15
NNE
20
NNE
20
NNE
20
NE
20
NNE
15
NNE
10
E
5
SE
15
SSW
15
SSW
20
SW
10
SW
15
SSW
15
WSW
Wind State
cross-on
cross-on
off
off
cross-off
off
off
cross-off
off
cross-off
cross-off
off
off
cross
glassy
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
High Tide
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
6:45AM1.29m
6:03PM1.43m
Low Tide
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
12:11PM0.69m
00:53AM0.27m
thunderstorm
thunderstorm
heavy rain
light rain
light rain
light rain
cloud
light rain
light rain
light rain
cloud
cloud
part cloud
clear
thunderstorm
cloud
light rain
rain showers
rain showers
thunderstorm
thunderstorm
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:16
5:16
5:16
5:18
5:18
5:18
5:20
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
5:54
5:53
5:52
5:51
5:49
5:47
5:46
 mm
2
5
14
5
1
4
2
5
1
2
1
1
1
2
1
Temp °C
29
28
23
21
21
21
20
21
21
22
23
23
25
25
25
26
25
25
27
27
26
Feels °C
28
27
22
20
20
20
20
22
21
23
24
24
28
28
29
28
27
26
30
29
29
  • 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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