Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 pm 23 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
27.8°C
1.0° 

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


Onjuku surf forecast from 23 Aug 2026:

  • Best quality surf: Monday 24 Aug, 6AM (local time) - 2.5ft (0.8m), 18s period, SSE swell with glassy winds.
  • Most powerful swell: Monday 24 Aug, 3PM (local time) - 6ft (1.8m), 16s period, SSE swell with 1,634 kJ wave energy.
  • Next surfable swell (1★+): Monday 24 Aug, 12AM (local time) - 2.5ft (0.8m), 12s period with SSE 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 Monday (Aug 24) at 12AM. The primary swell is predicted to be 0.8m and 12s period with a secondary swell of 0.6m and 9s. The wind is predicted to be glassy as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 1.8m 16s and forecast to arrive on Monday (Aug 24) at 3PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.0m 5s period and expected on Saturday (Aug 29) at 12PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+)12AM (Mon 24th Aug)2.5ft (0.8m) 12s
Best Surf 6AM (Mon 24th Aug)2.5ft (0.8m) 18s
Most Powerful 3PM (Mon 24th Aug)6ft (1.8m) 16s

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


The Lowdown

Right, grab a seat, let’s see what’s cookin’ for Onjuku. It’s gonna be a bit of a mixed bag, but there’s a couple of real gems hiding in there if you’re patient.

First up, we’ve got a bit of a slow start. It’s not all bad, but don’t expect much for the first week or so. The water’s sitting at a warm 82°, which is about a degree and a half warmer than usual for this time of year – feels nice, doesn’t it?

Alright, let’s get into it. The standout, the one you’ve been waiting for, is Wednesday morning, 2nd September. The swell is coming in from the southeast at a solid 7ft, and the wind is a clean, light offshore from the ENE. That’s the kind of magic that makes a point break like Onjuku really shine. The wave energy is solid, with a combined energy of 934, so there’s plenty of push. It’s a short period swell at 9 seconds, so it’ll be a bit more peaky, but with that offshore wind, it’s gonna be clean and lined up. This one is the best of the bunch, no doubt.

The afternoon of the 2nd is still worth a look, with a 6ft swell from the SE, but the wind swings more cross-shore, making it a bit choppier. Still, a good backup.

Now, before that, there’s a long dry spell. From Sunday the 23rd right through to the end of the month, it’s mostly small, messy, and onshore. There’s a brief window on Thursday the 27th afternoon with a 2ft easterly swell and a clean cross-offshore wind, but it’s tiny. The few days after that are just small and ordinary, with a bit of a bump in the morning of the 2nd as the main event.

Looking further out, the 3rd and 4th of September have some promise. On the 3rd, we’ve got a 4ft swell from the south with a long period of 14 seconds, and a clean cross-offshore wind. That’s a nice, grunty groundswell, but it’s a bit smaller and the energy is around 872. The 4th brings a 4ft swell from the SSW with a 14-second period and a solid offshore wind from the NNE. That’s clean, but for the more experienced crew. The wave energy is a bit lower at 667.

After that, from the 5th onwards, it’s back to poor conditions with onshore winds and lumpy seas, so the window closes pretty quickly.

So, to sum it up: if you’re after the best, make your plans for the first few days of September. That Wednesday morning, 2nd September, is the one to book time off for. The 3rd and 4th are promising but less certain. The rest of the 16-day window is mostly a write-off, but hey, that’s how it goes sometimes.

Rusty.

Short Range Forecast

Mostly dry. Warm (max 29°C on Wed morning, min 25°C on Sun night). Winds increasing (calm on Sun night, fresh winds from the SW by Tue night).

Days 5-7 Weather Summary

Heavy rain (total 32mm), heaviest during Thu morning. Warm (max 29°C on Wed afternoon, min 21°C on Thu night). Wind will be generally light.

Sun
23
Monday
24
Tuesday
25
Wednesday
26
Thursday
27
Friday
28
Saturday
29
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
2
2
2
0
0
0
0
0
0
0
0
0
2
2
0
0
0
0
0
1
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
SSE
12
0.8
SSE
12
0.9
SSE
18
1.8
SSE
16
1.7
SSE
13
1.8
SSE
13
1.6
SSE
12
1
SSE
10
0.8
S
11
0.8
SSW
12
0.9
SSE
10
1.3
SSW
6
0.7
E
13
0.7
E
13
0.7
E
12
0.7
E
12
0.6
E
12
0.6
E
11
0.6
E
12
0.6
E
12
Wave Graph
Metric surfscale
Energy kJ
104
196
459
1634
950
1025
768
202
163
198
166
100
173
163
148
137
98
88
98
98
Wind (km/h)
10
ENE
0
NNE
5
SSW
20
SSW
25
SW
25
SW
30
SSW
30
SW
20
SW
30
SW
20
SW
15
WSW
15
NE
10
N
20
SW
25
SW
10
WSW
15
NE
20
NE
10
N
Wind State
cross-off
glassy
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-off
off
cross-on
cross-on
cross
cross-off
cross-off
off
High Tide
4:31PM1.15m
11:58PM1.18m
4:19PM1.20m
1:32AM1.23m
4:27PM1.25m
2:31AM1.30m
4:41PM1.29m
3:17AM1.37m
4:57PM1.33m
3:58AM1.42m
5:14PM1.37m
4:38AM1.44m
5:32PM1.40m
Low Tide
7:50PM1.12m
8:27AM0.35m
8:48PM1.04m
9:08AM0.28m
9:22PM0.95m
9:42AM0.22m
9:51PM0.85m
10:12AM0.19m
10:21PM0.74m
10:41AM0.20m
10:51PM0.63m
11:09AM0.24m
11:22PM0.53m
part cloud
clear
clear
clear
clear
clear
clear
clear
part cloud
part cloud
thunderstorm
mod rain
mod rain
heavy rain
part cloud
part cloud
part cloud
thunderstorm
part cloud
part cloud
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:03
5:05
5:05
5:05
5:07
5:07
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:17
6:16
6:15
6:14
6:13
6:12
6:09
 mm
1
8
8
14
1
Temp °C
27
25
28
28
26
28
28
27
29
29
27
27
25
23
27
27
25
26
26
24
Feels °C
30
29
30
29
28
29
28
27
31
30
29
31
27
25
27
27
27
28
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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