Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 am 19 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
26.8° C
0.0° 

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


Onjuku surf forecast from 18 Aug 2026:

  • Best quality surf: Sunday 23 Aug, 12AM (local time) - 3.5ft (1.0m), 10s period, E swell with offshore winds.
  • Most powerful swell: Wednesday 26 Aug, 9AM (local time) - 8ft (2.5m), 17s period, S swell with 4,173 kJ wave energy.
  • Next surfable swell (1★+): Wednesday 19 Aug, 6AM (local time) - 2ft (0.6m), 8s 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 Wednesday (Aug 19) at 6AM. The primary swell is predicted to be 0.6m and 8s period with a secondary swell of 0.6m and 6s. The wind is predicted to be glassy as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 2.5m 17s and forecast to arrive on Wednesday (Aug 26) at 9AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.7m 4s period and expected on Sunday (Aug 23) at 9AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 6AM (Wed 19th Aug)2ft (0.6m) 8s
Best Surf12AM (Sun 23rd Aug)3.5ft (1.0m) 10s
Most Powerful 9AM (Wed 26th Aug)8ft (2.5m) 17s

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


The Lowdown

Alright folks, Rusty here. Let's break down what's shakin' for Onjuku over the next couple weeks.

Truth be told, the first week-plus is a grind. We've got persistent cross-onshore wind and small, weak, junky swell. The first real chance of a wave comes on Sunday, August 23rd. That morning, the wind goes glassy, and we get a clean 3ft east swell with moderate energy. It's not gonna blow your mind, but it'll be clean and rideable. Just remember, this spot is inconsistent, so you'll be waiting between sets.

After that, it's back to poor conditions until Tuesday, August 25th. Tuesday morning brings a clean 2-3ft swell from the ESE with a very long 14-second period and light onshore wind. That's real groundswell energy, so it'll have good punch, but at a beach break it might wall up a bit.

Now for the big one, and I mean *big*. Sunday, August 30th. Onjuku gets absolutely slammed with a 12ft SE swell. The energy readings are insane. The wind is cross-shore and then cross-offshore, and the conditions get clean. HOWEVER – and this is critical – 12ft is massive. This is expert-only territory. Beginners, don't even think about it. If you've got the skill, this is the best setup of the whole forecast, but it's a long way out, so keep your hopes in check.

That huge swell sticks around into early September, still over 10ft with offshore or clean sideshore winds on the 1st and 2nd. Same story – experts only.

So, the call: the standout is that massive SE groundswell kicking off around August 30th. It's big, it's clean, it's powerful. Everything before that is small, inconsistent, or blown out. For the average surfer, that glassy 3ft day on the 23rd is your only solid bet.

This is Rusty, signing off.

Short Range Forecast

Some drizzle, heaviest during Fri night. Warm (max 28°C on Fri morning, min 25°C on Wed night). Wind will be generally light.

Days 4-6 Weather Summary

Mostly dry. Warm (max 29°C on Sat morning, min 24°C on Sat night). Wind will be generally light.

Wednesday
19
Thursday
20
Friday
21
Saturday
22
Sunday
23
Monday
24
Tuesday
25
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
0
0
0
0
0
2
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)
0.4
SE
10
0.5
E
9
0.5
E
9
0.4
SE
10
0.4
SE
11
0.4
SE
11
0.5
S
9
0.4
SE
10
0.6
E
9
0.8
E
11
1
E
10
1
E
10
0.8
E
10
0.7
E
9
0.7
E
9
0.5
E
12
0.7
SSE
14
0.9
SSE
17
1.8
SSE
15
2
SSE
14
2.4
SSE
15
Wave Graph
Metric surfscale
Energy kJ
35
36
37
39
40
40
40
39
58
151
221
198
120
80
78
69
186
427
1432
1598
2688
Wind (km/h)
5
ESE
15
SE
5
SSE
10
SE
10
SSE
10
S
10
SSW
20
SSW
20
SW
15
SW
20
SSW
5
N
15
NE
15
ENE
5
NNE
0
E
15
SSW
20
SW
25
SW
25
SSW
20
SSW
Wind State
cross-on
cross-on
cross-on
cross-on
on
on
on
on
cross-on
cross-on
cross-on
off
cross-off
cross-off
off
glassy
on
cross-on
cross-on
cross-on
cross-on
High Tide
7:42PM1.36m
9:58AM0.96m
8:05PM1.32m
8:35PM1.27m
9:35PM1.21m
4:31PM1.15m
11:58PM1.18m
4:19PM1.20m
1:32AM1.23m
4:27PM1.25m
2:31AM1.30m
Low Tide
1:24PM0.80m
3:09AM0.46m
1:21PM0.89m
4:20AM0.49m
6:00AM0.49m
7:29AM0.43m
7:50PM1.12m
8:27AM0.35m
8:48PM1.04m
9:08AM0.28m
9:22PM0.95m
clear
part cloud
clear
part cloud
part cloud
part cloud
part cloud
part cloud
rain showers
part cloud
part cloud
part cloud
part cloud
part cloud
clear
part cloud
clear
clear
clear
clear
clear
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:00
5:01
5:01
5:01
5:03
5:03
5:05
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:22
6:22
6:21
6:19
6:17
6:16
6:15
 mm
1
Temp °C
27
27
26
27
27
26
28
27
26
29
29
26
26
26
25
27
28
26
28
28
26
Feels °C
30
29
29
30
29
29
29
28
28
30
30
29
29
28
28
32
30
28
27
27
28
  • 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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