Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 pm 02 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
26.0°C
0.6° 

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


Onjuku surf forecast from 2 Sep 2026:

  • Best quality surf: Friday 4 Sep, 3AM (local time) - 3.5ft (1.0m), 6s period, ENE swell with cross-offshore winds.
  • Most powerful swell: Wednesday 9 Sep, 3AM (local time) - 11ft (3.5m), 12s period, SSE swell with 3,811 kJ wave energy.
  • Next surfable swell (1★+): Friday 4 Sep, 3AM (local time) - 3.5ft (1.0m), 6s 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 04) at 3AM. The primary swell is predicted to be 1.0m and 6s period with a secondary swell of 0.6m and 6s. The wind is predicted to be cross-offshore as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 3.5m 12s and forecast to arrive on Wednesday (Sep 09) at 3AM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.7m 6s period and expected on Sunday (Sep 06) at 3AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 3AM (Fri 4th Sep)3.5ft (1.0m) 6s
Best Surf 3AM (Fri 4th Sep)3.5ft (1.0m) 6s
Most Powerful 3AM (Wed 9th Sep)11ft (3.5m) 12s

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


The Lowdown

Alright, Rusty here. Let’s talk about what’s happening at Onjuku. I’ll be straight with you – the next 16 days are a real mixed bag, with a whole lot of nothing at the start and then some heavyweight stuff later on that’ll test your nerve.

Right now and through the first several days, there’s just not much to get excited about. We’re looking at small, weak surf with poor conditions from Thursday (the 3rd) well into next week. The first few days have waves under 3 ft with a combined swell energy of just 160 to 199, and the wind is cross-on or just messy. You’d be fighting a losing battle. The water temp is about average for this time of year, nothing unusual to report.

We hit a bit of a turning point around Sunday the 6th into Monday the 7th, but it’s still far from perfect. The swell jumps up to 8 ft to 8 ft, coming from the E with a short period of 7 seconds. That’s a lot of water moving fast with not much shape. The combined energy climbs to 641 and 865, but the wind is strong offshore and clean. This is marginal at best, and honestly, at that size with that short a period, it’s a bit of a washing machine. Not for the faint-hearted.

There’s a real wildcard Tuesday the 8th, but don’t get your hopes up. The swell is 8 ft from the S, period of 10 seconds, and the combined energy is a massive 2052, but the wind is a strong cross-onshore. It’s lumpy and messy. Then Wednesday the 9th sees the biggest swell of the whole outlook – a solid 13 ft from the SSE with an 11-second period. The energy readings are off the charts at 3278 and 3444, but the wind is howling onshore at 22-25 mph. This is pure chaos, and unless you’re a total expert on a big-wave setup and don't mind a beating, give it a miss. It looks more like a kite surfing day than a paddle surfing day.

After that, things slowly settle. From the 11th to the 14th, we get some cleaner conditions with cross-off winds but the surf drops back to 3 ft to 5 ft, with energy dropping to the 300-600 range. It’s still marginal, with the odd clean window but nothing that screams “go now”.

The one true standout is the early morning of Tuesday the 15th. This is your best bet. We’ve got a 5 ft swell from the ESE with a solid 10-second period. The combined energy is 558, so moderate and punchy, but the big news is the wind – it’s true offshore from the NNE at 19 mph. That means clean, lined-up waves at Onjuku. The break is exposed and likes a SSE swell, so this ESE direction is a bit off-angle, but the quality of the wind and the consistency makes this the pick of the week. Crowds are sometimes an issue here, so get in early.

Later in the second week, the 18th (Friday morning) pops up with a 6 ft SSE groundswell and a very long 15-second period. The energy is a beastly 3005. This is a big, powerful, clean swell but with that long period, it might throw up some walls at the beach break – better suited for a point or reef if you can find one. The wind is offshore and clean, making it a promising but less certain long-range call.

So, to sum it up: The first week is a write-off, and the middle is either too big and blown out or too small. Your only real windows are Tuesday the 15th morning for a clean, solid session, and maybe a look at Friday the 18th morning if you’re feeling bold and the forecast holds.

Stay safe out there, Rusty.

Short Range Forecast

Heavy rain (total 98mm), heaviest during Fri night. Warm (max 29°C on Thu morning, min 21°C on Fri night). Winds increasing (light winds from the S on Wed night, fresh winds from the NE by Fri night).

Days 5-7 Weather Summary

Heavy rain (total 111mm), heaviest during Sun morning. Warm (max 28°C on Mon morning, min 22°C on Sat night). Winds increasing (light winds from the WSW on Sun night, strong winds from the S by Tue afternoon).

Thursday
3
Friday
4
Saturday
5
Sunday
6
Monday
7
Tuesday
8
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
0
0
0
0
0
1
1
1
1
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)
0.6
E
11
0.7
E
10
0.8
S
8
0.5
E
10
0.5
S
10
0.6
S
10
0.6
S
9
0.5
S
10
1.3
ESE
7
1.5
E
7
2.4
E
7
2.5
E
8
3
ESE
8
2.3
ESE
8
1.6
E
8
1.7
S
8
2.3
S
10
2.2
S
10
3
SSE
12
Wave Graph
Metric surfscale
Energy kJ
88
98
90
48
51
71
61
48
142
196
603
826
1121
670
343
383
1087
882
2314
Wind (km/h)
10
S
20
SSW
25
SSW
20
ENE
15
NE
20
NE
30
NNE
25
NE
25
NNE
35
NNE
35
ENE
30
ENE
20
ESE
15
SSW
25
S
25
SSE
30
SSE
40
SSE
45
S
Wind State
on
cross-on
cross-on
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-on
on
on
on
cross-on
on
on
High Tide
8:31AM1.12m
7:17PM1.40m
10:14AM1.02m
7:46PM1.36m
8:26PM1.30m
4:09PM1.19m
10:16PM1.23m
3:44PM1.25m
00:42AM1.25m
3:57PM1.30m
2:06AM1.33m
Low Tide
1:54AM0.31m
1:12PM0.84m
2:52AM0.34m
1:18PM0.97m
4:13AM0.36m
6:01AM0.34m
6:12PM1.19m
7:30AM0.27m
8:17PM1.09m
8:30AM0.20m
8:59PM0.95m
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part cloud
thunderstorm
rain showers
thunderstorm
light rain
heavy rain
heavy rain
heavy rain
heavy rain
heavy rain
heavy rain
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
mod rain
thunderstorm
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:11
5:11
5:13
5:13
5:13
5:15
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:05
6:04
6:01
6:00
5:59
5:58
5:57
 mm
1
3
2
2
61
18
11
19
18
12
21
8
6
15
5
7
4
Temp °C
27
29
28
24
25
25
23
23
23
24
24
24
26
28
28
27
28
28
28
Feels °C
31
31
30
23
27
26
23
23
22
23
23
23
28
29
30
28
27
27
26
  • 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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