Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 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, 6AM (local time) - 2.5ft (0.8m), 18s 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 6AM. The primary swell is predicted to be 0.8m and 18s period with a secondary swell of 0.9m and 12s. 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 1.1m 5s period and expected on Saturday (Aug 29) at 3PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 6AM (Mon 24th Aug)2.5ft (0.8m) 18s
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

Alright, this is Rusty. Let's have a look at what's on the table for the next couple of weeks.

Alright, so we're looking at a pretty bleak start, if I'm being honest. The next few days are a write-off for anything decent. We've got a bit of a swell on the Monday morning, but it's all downhill from there until we get into the first week of September. The standout – and I mean the only real standout – is that Monday morning session on the 24th of August. After that, there's a massive gap of nearly two weeks of poor to marginal conditions.

Onjuku is the only spot in the picture, and it's an exposed beach break that's inconsistent. The best of the whole 16-day window is hands down the Monday morning, 24th of August. The conditions are going to be absolutely perfect. We've got a clean 3ft groundswell rolling in from the SSE, with a super long 18-second period. The combined energy is moderate at 944, but that long period will give you some proper, well-shaped waves with nice long lulls between sets. The absolute key here is the wind: it's glassy, dead calm, with a slight offshore flow from the SSW. The water temp is about average for the time of year. It’s a rare treat for a spot that's inconsistent, so you’ve got to be on it. The crowd factor is "sometimes", so it could be a bit busy, but with that quality, it's worth the paddle.

The afternoon of the 24th gets a bit choppy as the wind picks up, and the rest of that week is just a mess of cross-onshore winds and dropping swell – nothing to get excited about.

The next real glimmer doesn't come until Monday, 7th of September. That morning, the wind drops to glassy again, with a clean 4ft swell from the S at a 12-second period. The combined energy is moderate (619). This is a promising one, but it's a long way off, so treat it as a hopeful line on the calendar rather than a guarantee. The afternoon gets a bit of a cross-onshore breeze, but the morning should be a solid session.

The rest of the early September period is a mix of small, weak swells and strong winds, mostly from the NE. The 3rd of September has a short, messy 6ft windswell from the NE with a period of only 6 seconds – that's junk, and it's gonna be more of a kite-surfing day than a proper paddle session. The following days are just more of the same: small, wind-affected, and inconsistent.

So, to wrap it up: you've got one absolute cracker on Monday morning, 24th of August, and a potential second one on the horizon for Monday morning, 7th of September. Everything else in between is a long, flat stretch of poor conditions. If you can get out for that first one, do it. It’s the only real gold in this patch.

Rusty.

Short Range Forecast

Mostly dry. Warm (max 30°C on Wed morning, min 25°C on Sun night). Winds increasing (calm on Mon morning, fresh winds from the SW by Tue night).

Days 5-7 Weather Summary

Heavy rain (total 31mm), heaviest during Thu night. Warm (max 29°C on Thu morning, min 22°C on Thu night). Winds decreasing (fresh winds from the SW on Wed night, calm by Thu afternoon).

Monday
24
Tuesday
25
Wednesday
26
Thursday
27
Friday
28
Saturday
29
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
2
3
1
0
0
0
0
0
0
0
0
2
2
0
0
0
1
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)
0.8
SSE
12
0.9
SSE
18
1.8
SSE
16
1.6
SSE
13
1.7
SSE
13
1.7
SSE
12
1.3
S
12
0.9
SSW
12
0.8
SSW
12
1.4
SSW
6
0.7
SSE
10
0.7
E
13
0.7
E
13
0.9
S
8
0.6
E
12
0.6
E
12
0.6
E
11
0.5
E
11
0.5
E
12
Wave Graph
Metric surfscale
Energy kJ
196
459
1634
841
903
876
496
228
208
124
98
173
176
112
103
99
93
63
66
Wind (km/h)
5
NNE
0
SSW
20
SSW
25
SW
25
SW
30
SW
30
SW
20
SW
30
SW
30
SW
20
SW
5
W
15
NE
20
SW
25
SW
15
SW
10
N
20
NE
15
NNE
Wind State
glassy
glassy
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
glassy
cross-off
cross-on
cross-on
cross-on
off
cross-off
cross-off
High Tide
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
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
part cloud
clear
part cloud
thunderstorm
thunderstorm
thunderstorm
part cloud
part cloud
thunderstorm
thunderstorm
cloud
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
5
6
15
2
3
Temp °C
25
28
28
26
28
28
27
30
29
27
29
27
25
28
27
26
26
24
23
Feels °C
29
30
30
28
28
28
27
31
30
28
32
32
28
28
27
28
29
25
24
  • 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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