Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 am 02 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
26.8°C
0.2° 

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: Tuesday 8 Sep, 6PM (local time) - 15ft (4.5m), 12s period, SSE swell with onshore winds.
  • Most powerful swell: Tuesday 8 Sep, 9PM (local time) - 16ft (5.0m), 11s period, SSE swell with 5,812 kJ wave energy.
  • Next surfable swell (1★+): Thursday 3 Sep, 9PM (local time) - 2ft (0.6m), 10s 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 Thursday (Sep 03) at 9PM. The primary swell is predicted to be 0.6m and 10s period with a secondary swell of 0.8m 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 5.0m 11s and forecast to arrive on Tuesday (Sep 08) at 9PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.2m 5s period and expected on Sunday (Sep 06) at 9AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 9PM (Thu 3rd Sep)2ft (0.6m) 10s
Best Surf 6PM (Tue 8th Sep)15ft (4.5m) 12s
Most Powerful 9PM (Tue 8th Sep)16ft (5.0m) 11s

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


The Lowdown

Alright folks, Rusty here. Let’s be real – the next couple of weeks at Onjuku are a tough watch. We’re talking a solid run of messy, blown-out conditions with a few bright spots. The water is sitting at 80°, which is pretty much exactly what you’d expect for this time of year, so no surprises there.

The first few days are a write-off. We’ve got a mix of cross-onshore winds and poor surf quality from Wednesday morning through to Sunday afternoon. The swell is small and weak, never really getting its act together. The combined energy is low, hovering around 150-200 (weak), so you’re looking at tiny, bumpy waves. Not worth paddling out for.

Friday morning, September 4th, things get a little interesting. The wind drops to glassy, and the swell is small but rideable. The energy is still weak (150mm), but it’s clean. It’s surfable, but nothing to get excited about. Friday afternoon and Saturday morning stay clean, but the swell stays stubbornly small and weak.

Sunday, September 6th, sees a jump in size, but the wind picks up to a fresh breeze, and the quality is poor. By Sunday afternoon, the swell hits 7ft, but it’s short period (7 seconds) and messy. The energy is moderate (403mm), but it’s just not breaking well.

The following week is a washout. From Monday, September 7th, through to Thursday, September 10th, we’ve got constant onshore winds, risk of thunderstorms, and the swell is too big and lumpy for Onjuku to handle. The energy spikes into the strong to very strong range from Tuesday, September 8th, onwards, with values like 1688mm and 3138mm, but it’s all for nothing – the wind is ruining it.

The standout moment comes on Wednesday, September 9th, in the morning. The wind is light, the swell is a solid 12ft from the south, and the period is 11 seconds. The combined energy is a massive 5503mm (very strong). The setup is clean, but here’s the catch: the swell is predicted to be too big for this break. This is one for the experts only. If you’re a confident, experienced surfer, it could be a wild ride, but for everyone else, stay on the beach.

We then hit another gap of poor conditions until Monday, September 14th, afternoon. The wind is cross-off, the swell is a modest 4ft from the southeast, and the energy is moderate (639mm). It’s a marginal call, but it’s clean and rideable for the average surfer.

The best swell of the entire forecast arrives on Tuesday, September 15th, and Wednesday, September 16th. We’re looking at 13ft to 16ft swell from the southeast, with long periods of 13-14 seconds. The energy is off the charts (7641mm and 6838mm). The wind is offshore, and the conditions are glassy. But again, this is massive. 13ft+ with a long period is a serious, heavy wave, and it’s likely too big and powerful for this beach break. The swell direction is southeast, which is not the optimum for Onjuku (which prefers SSE). This is a solid, promising, but dangerous setup for the most experienced locals only.

The last few days of the period, September 17th, offer a decent drop-off with 7ft to 8ft swell and clean conditions, but the energy is still strong, and the wind shifts onshore in the afternoon. It’s a window, but not a standout.

Honestly, if you’re not an expert, the next two weeks are a bust. The best on offer is that Wednesday morning, September 9th, for the big-wave crew, and maybe the Tuesday, September 15th, for the absolute elite. For everyone else, keep your board in the car and wait for the next window.

Rusty.

Short Range Forecast

Heavy rain (total 113mm), heaviest during Fri afternoon. Warm (max 27°C on Wed morning, min 21°C on Fri night). Wind will be generally light.

Days 4-6 Weather Summary

Heavy rain (total 93mm), heaviest during Sun night. Warm (max 28°C on Mon morning, min 22°C on Sun afternoon). Winds increasing (light winds from the SSE on Sun night, strong winds from the S by Mon night).

Wednesday
2
Thursday
3
Friday
4
Saturday
5
Sunday
6
Monday
7
Tuesday
8
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
0
1
1
2
1
0
0
0
0
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)
0.9
ESE
10
1.1
E
10
0.6
E
11
0.7
E
10
0.8
S
8
0.6
E
10
0.6
S
10
0.6
S
10
0.9
SSW
9
0.8
S
9
0.6
S
9
1
E
5
1
ESE
7
2
E
7
2.2
E
8
1.8
ESE
7
1.5
E
8
1.8
SSE
9
2.5
SSE
11
3.5
SSE
12
4.5
SSE
11
Wave Graph
Metric surfscale
Energy kJ
146
240
88
98
90
68
74
71
126
99
56
57
93
382
534
365
249
455
1518
3129
4940
Wind (km/h)
10
SE
10
SE
10
SSE
15
SSW
15
SSW
20
NNE
5
ESE
15
NE
25
NNE
20
NE
20
ENE
25
ENE
35
ENE
35
ENE
35
E
20
SSE
35
SSE
50
S
30
S
25
S
15
S
Wind State
cross-on
cross-on
on
cross-on
on
cross-off
glassy
cross-off
off
cross-off
cross-off
cross-off
cross-off
cross-off
cross
on
cross-on
on
on
on
on
High Tide
6:53PM1.43m
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
12:52PM0.70m
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
part cloud
part cloud
light rain
thunderstorm
thunderstorm
mod rain
heavy rain
heavy rain
heavy rain
part cloud
clear
part cloud
light rain
mod rain
heavy rain
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:11
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
2
2
3
10
28
51
17
3
9
53
10
9
9
3
10
19
Temp °C
27
27
26
27
27
26
23
22
21
24
24
24
24
22
26
28
27
27
28
28
27
Feels °C
30
29
29
30
30
29
27
24
19
23
23
22
21
19
29
30
27
25
29
30
30
  • 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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