Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 pm 24 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
28.0°C
1.2° 

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


Onjuku surf forecast from 24 Aug 2026:

  • Best quality surf: Thursday 27 Aug, 12PM (local time) - 2.5ft (0.8m), 10s period, SSE swell with cross-offshore winds.
  • Most powerful swell: Tuesday 25 Aug, 6AM (local time) - 6ft (1.9m), 13s period, SSE swell with 1,211 kJ wave energy.
  • Next surfable swell (1★+): Thursday 27 Aug, 12PM (local time) - 2.5ft (0.8m), 10s 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 Thursday (Aug 27) at 12PM. The primary swell is predicted to be 0.8m 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 1.9m 13s and forecast to arrive on Tuesday (Aug 25) at 6AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.8m 4s period and expected on Saturday (Aug 29) at 12PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+)12PM (Thu 27th Aug)2.5ft (0.8m) 10s
Best Surf12PM (Thu 27th Aug)2.5ft (0.8m) 10s
Most Powerful 6AM (Tue 25th Aug)6ft (1.9m) 13s

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


The Lowdown

Alright, let’s have a look at what’s shaping up for Onjuku over the next couple of weeks. It’s a bit of a mixed bag, to be honest. We’ve got a fair stretch of poor conditions ahead, but there are a few windows that should get you excited, especially if you’re willing to wait.

Right now, and for the first few days, it’s pretty grim. Tuesday the 25th and Wednesday the 26th are a write-off with moderate to fresh cross-onshore winds and messy, choppy surf. The swell is there, but the wind has got it all torn up. On Thursday the 27th morning, we’ve got a short-period 5ft SW swell, but it’s still cross-on and choppy. The afternoon sees a drop to small 2ft but with clean conditions from a light cross-off breeze. It’s marginal, but you might find a ripple.

Then we get to the first real standout. Friday morning, the 28th of August. This is the one to point your board at. We’ve got a 2ft east swell rolling in with a clean 12-second period, and the wind is forecast to be glassy. Absolutely glassy. It’s going to be smooth, clean, and fun for an intermediate. The water temp is about average for this time of year, so no surprises there. The combined swell energy is moderate at 288, so there’s enough to push you around. Just be aware it’s an inconsistent break, and crowds are possible, so get in early.

After that little gem, things drop off again. Saturday the 29th through Monday the 31st of August, the swell fades to 2ft to 2ft. The wind is mostly cross-off and clean, but the energy just isn’t there to make it worthwhile. It’s a bit of a flat spell. Tuesday the 1st of September morning shows some promise with a 2ft S swell, 11-second period, and clean conditions, but the afternoon turns onshore and messy. Wednesday the 2nd is a no-go with onshore winds and building, but poor quality surf.

Thursday the 3rd keeps up the poor theme, but then we get another chance. Friday morning, the 4th of September. This is your second standout. There’s a 4ft south swell, short period at 6 seconds, but the wind is a light cross-off from the northwest giving clean conditions. It’s not big, but it’s clean and surfable. The energy is moderate at 232. Saturday the 5th morning has a small clean offshore window, but again, pretty ordinary.

Now, a heads up for the second week. Sunday the 6th and Monday the 7th of September see a big, powerful, and messy swell arrive. We’re talking 8ft to 13ft SSE/S swell with very strong wave energy (over 2700), but the wind is mostly cross-on to onshore, making it poor and dangerous. That kind of size and power is for experts only, and with the onshore wind, it’s a washout. Tuesday the 8th afternoon finally cleans up with a light cross-off and a solid 8ft SSE swell, giving excellent conditions for experienced surfers. That’s a big, powerful option but not for the faint-hearted. Wednesday the 9th fades back down into poor surf.

So, the best on offer is that glassy Friday morning on the 28th for a clean, cruisy session, and that clean Friday morning on the 4th of September for a bit more push. If you’re an experienced surfer, keep an eye on Tuesday the 8th afternoon for some proper, powerful waves once the wind settles.

Rusty.

Short Range Forecast

Light rain (total 5mm), mostly falling on Thu morning. Warm (max 30°C on Wed morning, min 24°C on Thu afternoon). Mainly fresh winds.

Days 5-7 Weather Summary

Light rain (total 4mm), mostly falling on Thu night. Warm (max 28°C on Fri morning, min 24°C on Thu night). Wind will be generally light.

Tuesday
25
Wednesday
26
Thursday
27
Friday
28
Saturday
29
Sunday
30
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
1
1
2
0
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)
1.6
SSE
13
1.8
SSE
13
1.6
SSE
12
1
S
12
0.9
SSE
10
0.7
SSW
12
1.3
SSW
6
1.4
SW
6
0.7
E
13
0.7
E
13
0.7
E
12
0.9
SSW
8
0.6
E
12
0.6
E
12
0.5
E
11
0.5
E
11
0.5
E
12
0.6
E
12
0.6
E
11
Wave Graph
Metric surfscale
Energy kJ
878
1025
658
287
159
147
111
131
173
163
148
119
106
96
63
61
65
98
89
Wind (km/h)
20
SW
25
SW
30
SW
30
SW
20
SW
30
SW
30
SW
20
WSW
20
NE
5
ESE
5
NNW
20
SSW
5
NW
20
NE
20
NE
20
NNE
20
NNE
15
NE
15
NNE
Wind State
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-off
cross
glassy
cross-on
glassy
cross-off
cross-off
cross-off
cross-off
cross-off
off
High Tide
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
5:17AM1.43m
5:51PM1.42m
Low Tide
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
11:35AM0.32m
11:54PM0.43m
clear
clear
clear
clear
clear
clear
part cloud
thunderstorm
light rain
light rain
part cloud
part cloud
part cloud
part cloud
thunderstorm
rain showers
part cloud
part cloud
part cloud
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:05
5:05
5:05
5:07
5:07
5:07
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:16
6:15
6:14
6:13
6:12
6:09
6:08
 mm
3
2
2
1
1
Temp °C
26
28
28
27
30
29
27
29
24
25
28
28
26
27
26
25
26
26
24
Feels °C
28
29
28
28
31
30
27
32
25
29
31
30
30
28
27
27
27
28
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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