Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 pm 26 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 26 Aug 2026:

  • Best quality surf: Tuesday 1 Sep, 6PM (local time) - 4ft (1.2m), 12s period, S swell with cross-offshore winds.
  • Most powerful swell: Wednesday 2 Sep, 9PM (local time) - 4.5ft (1.4m), 12s period, S swell with 556 kJ wave energy.
  • Next surfable swell (1★+): Thursday 27 Aug, 3PM (local time) - 2.5ft (0.7m), 13s 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 (Aug 27) at 3PM. The primary swell is predicted to be 0.7m and 13s period with a secondary swell of 0.8m and 6s. Another secondary swell of 1.1m and 5s is also forecast. 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 1.4m 12s and forecast to arrive on Wednesday (Sep 02) 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 Monday (Aug 31) at 6AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 3PM (Thu 27th Aug)2.5ft (0.7m) 13s
Best Surf 6PM (Tue 1st Sep)4ft (1.2m) 12s
Most Powerful 9PM (Wed 2nd Sep)4.5ft (1.4m) 12s

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


The Lowdown

Alright folks, grab a coffee. For the next couple of weeks, Onjuku is playing a bit of a waiting game. The good news is, there’s some proper swell moving in later on, but the wind’s gonna be the main character for a while—and not in a good way. Water temp is sitting around 82°, which is a touch warmer than normal for this time of year.

Wednesday 26th – Forget about it today. We’ve got a swell at 3 ft from the SSE, but that cross-onshore SW wind at 18 mph has got it all lumpy and messy. Combined energy is moderate (410), but the quality is just poor.

Thursday 27th – A mixed bag. Morning is a write-off with stormy vibes and a choppy 4 ft SW swell. But look... Thursday afternoon has a glimmer. That tiny 2 ft E swell has a proper long period (13 seconds) and the wind swings light WNW, going cross-off. It’s going to be clean. Shame about the size, but for a sneaky session, that’s your best bet on this day.

Friday 28th – Rough morning with light onshore wind and a questionable tide. Afternoon builds to 4 ft from the SW, but with a junky 6-second period and cross-on wind, it’s a no-go. Leave it.

Saturday 29th through Monday 31st – A long, quiet stretch. We’re looking at tiny waves, mostly under 2 ft, and weak energy readings in the double digits (87 to 171). The wind is mostly cross-off, keeping it clean, but there’s simply no power. Perfect for a float, not for a surf.

Tuesday 1st September – Now we’re cooking. This is the first standout of the whole forecast. The morning brings a 3 ft S swell with a solid 12-second period, and the energy jumps to a strong 514. Wind is NE at 12 mph, cross-off, so it’s gonna be clean. The waves will have some proper shape. This is a real chance for some fun, lined-up waves.

Wednesday 2nd September – Building to 4 ft from the S, but the wind turns cross-onshore from the SSE at 15 mph, and the rain showers ruin the party. The energy is there (658), but the wind chops it up.

Thursday 3rd September – Swell hits 6 ft from the S, combined energy at 962. This is a proper pulse. But the wind is howling onshore at 18 mph, making it bumpy and messy. Too big and too windy for a pleasant paddle. If you’re a kite surfer, this might look interesting.

Friday 4th through Sunday 7th – A big drop-off. Swell stays around 3 ft to 4 ft, but the wind is consistently onshore or cross-onshore, and the energy drops back to the low hundreds to mid-400s. The quality is poor across the board. A total write-off.

Monday 8th September – This is the best session of the whole 16-day window. Mark it in your calendars. We’ve got a 5 ft SSE groundswell, and the period is a lovely 12 seconds. That’s proper. The wind in the morning is a light NE cross-off, and in the afternoon it goes glassy at 3 mph from the ESE. Combined energy is 631 and 594. The waves will be clean, groomed, and have some push. Onjuku is exposed to this SSE swell, so it’ll pick it up nicely. Expect some good lines, but be aware it might get a little busy—crowds are sometimes a thing here.

Tuesday 9th September – Still very decent. A 4 ft S swell with 12-second period, and you’ve got another glassy afternoon with 3 mph wind from the east. Combined energy is strong (541 to 633). The morning has a light cross-on breeze, but it’s manageable. A solid follow-up day.

Wednesday 10th September – And then we’re done. Swell direction swings SSW, period goes to 13 seconds, but the wind cranks up to 18 mph from the SW, cross-on. The energy is high (668-749), but the surf will be lumpy and tough to enjoy.

So to wrap it up: Monday 8th September is your absolute standout, with Tuesday 1st September being a close second for cleaner, smaller waves. The rest is wind-affected or flat. Get out there on those days.

Rusty.

Short Range Forecast

Heavy rain (total 28mm), heaviest during Thu night. Warm (max 29°C on Wed afternoon, min 24°C on Thu night). Winds decreasing (fresh winds from the SW on Wed night, calm by Fri night).

Days 5-7 Weather Summary

Some drizzle, heaviest during Mon morning. Warm (max 28°C on Sun afternoon, min 24°C on Sat night). Wind will be generally light.

Wed
26
Thursday
27
Friday
28
Saturday
29
Sunday
30
Monday
31
Tuesday
1
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
2
0
1
0
2
0
0
1
0
0
0
0
0
2
2
2
1
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.9
SSE
9
0.8
SSE
9
1.2
SW
6
0.7
E
13
0.7
E
13
0.7
E
12
1.3
SW
6
0.6
E
12
0.6
E
11
0.5
E
11
0.5
E
11
0.5
E
11
1.1
SSW
6
1.3
SW
6
0.4
E
11
0.5
S
11
0.5
S
14
1
S
12
1.1
S
12
1.3
S
12
Wave Graph
Metric surfscale
Energy kJ
146
113
98
173
163
148
114
99
94
63
61
62
77
141
37
58
91
301
347
510
Wind (km/h)
30
SW
30
SW
20
WSW
10
WNW
10
WSW
5
SSE
15
WSW
10
NNW
20
NE
20
ENE
10
ENE
10
SW
25
SW
25
SW
20
NNE
20
NE
10
NE
20
NE
15
ENE
15
SE
Wind State
cross-on
cross-on
cross-on
cross-off
cross-on
on
cross-on
off
cross-off
cross-off
cross-off
cross-on
cross-on
cross-on
cross-off
cross-off
cross-off
cross-off
cross-off
cross-on
High Tide
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
5:58AM1.39m
6:10PM1.43m
6:41AM1.32m
6:31PM1.44m
Low Tide
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
12:02PM0.43m
00:30AM0.36m
12:27PM0.56m
1:09AM0.32m
clear
part cloud
thunderstorm
thunderstorm
mod rain
thunderstorm
thunderstorm
rain showers
part cloud
cloud
part cloud
part cloud
part cloud
part cloud
light rain
part cloud
part cloud
part cloud
part cloud
thunderstorm
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:05
5:07
5:07
5:07
5:09
5:09
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:14
6:13
6:12
6:09
6:08
6:07
6:06
 mm
7
5
10
2
2
2
1
1
Temp °C
29
27
29
27
25
28
28
26
26
25
25
27
28
27
25
25
25
27
27
26
Feels °C
30
28
31
31
27
31
31
31
27
25
26
28
29
29
26
26
29
29
29
30
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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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