Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 am 11 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
27.4° C
0.7° 

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


Onjuku surf forecast from 10 Aug 2026:

  • Best quality surf: Sunday 16 Aug, 12AM (local time) - 11ft (3.5m), 11s period, ENE swell with offshore winds.
  • Most powerful swell: Sunday 16 Aug, 9AM (local time) - 13ft (4.0m), 11s period, NE swell with 3,607 kJ wave energy.
  • Next surfable swell (1★+): Wednesday 12 Aug, 12PM (local time) - 4ft (1.2m), 9s 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 12) at 12PM. The primary swell is predicted to be 1.2m and 9s period with a secondary swell of 0.5m and 10s. Another secondary swell of 0.9m 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 4.0m 11s and forecast to arrive on Sunday (Aug 16) at 9AM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.6m 4s period and expected on Monday (Aug 17) at 9AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+)12PM (Wed 12th Aug)4ft (1.2m) 9s
Best Surf12AM (Sun 16th Aug)11ft (3.5m) 11s
Most Powerful 9AM (Sun 16th Aug)13ft (4.0m) 11s

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


The Lowdown

Alright, let me have a look at what’s coming up for us.

Right now, things are pretty average at Onjuku. The water temp is sitting around 81°F, which is pretty much normal for this time of year, nothing weird going on there. We’ve got a bit of a slow start, with the first few days offering very little that’s worth getting excited about.

Tuesday the 11th is a write-off. We’ve got some lumpy cross-onshore wind and poor conditions, so don’t bother. Wednesday the 12th afternoon is where it starts to get interesting – we get a gentle offshore breeze from the NNE, with chest to head high swell, around 4ft. The period is a bit short at 9 seconds, but it’s clean. The combined energy is moderate at 322. Thursday the 13th also looks clean with a cross-offshore breeze and 5ft waves from the east, period still short but the shape should be okay. The energy picks up a bit to 432 and 506 during the day.

Friday the 14th stays clean but the swell drops a touch to 5ft and 5ft, and the forecast is a bit iffy, so it’s not a standout. Saturday the 15th sees the swell building, but the wind gets gusty from the NNE at 19 mph, so it’s messy despite the size.

Now, Sunday the 16th is a big one, but it’s not for everyone. The swell is forecast to be a solid 13ft from the NE with a period of 11 seconds. The energy is massive at 5752. This is expert territory – it’s too big for most. The wind is light and clean in the morning, but the size is just huge for this break. Only for the very experienced.

Monday the 17th morning is the real standout of the whole run. We’ve got glassy conditions – wind is absolutely dead calm – with a 6ft swell from the ENE. The period is 9 seconds, so it’s a bit short period, but that glassy surface is a gift. The energy is moderate at 560. This is your best bet for the cleanest, most user-friendly surf of the forecast. Get out there early.

After that, it’s a long dry spell. From Tuesday the 18th all the way through to the end of the forecast on the 26th, conditions are mostly poor. The swell drops right off, with tiny waves under 3ft for days, and the wind is generally cross-onshore or onshore. A few mornings like Thursday the 22nd show small clean 2ft waves, but it’s really just ankle-snappers. There’s a bit of a bump in energy around the 26th with 4ft and 7ft swell, but it’s accompanied by a fresh cross-onshore breeze and lumpy conditions, so it’s going to be a mess.

Honestly, the early mornings of Saturday the 15th and especially Monday the 17th are your only real windows for a decent session in the next couple of weeks. The rest is pretty flat or blown out.

Stay stoked.

Rusty

Short Range Forecast

Heavy rain (total 103mm), heaviest during Tue afternoon. Warm (max 27°C on Thu morning, min 21°C on Tue night). Winds decreasing (fresh winds from the SSW on Tue afternoon, calm by Wed night).

Days 4-6 Weather Summary

Moderate rain (total 11mm), heaviest on Fri morning. Warm (max 28°C on Fri afternoon, min 22°C on Sat night). Winds decreasing (fresh winds from the NE on Sat morning, calm by Sun afternoon).

Tuesday
11
Wednesday
12
Thursday
13
Friday
14
Saturday
15
Sunday
16
Monday
17
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
3
0
0
0
2
2
2
2
3
1
1
3
1
2
!
!
!
3
3
3
1
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
2.1
E
10
2
E
12
1.5
E
11
1.1
E
9
1.2
E
9
1.3
E
9
1.5
E
9
1.5
E
10
1.6
E
10
1.5
E
10
1.4
E
10
1.5
E
10
2
E
9
2.4
E
9
3.5
ENE
11
4
NE
11
4
NE
10
2.3
ENE
10
1.7
ENE
9
2.3
NE
9
1.4
ENE
9
Wave Graph
Metric surfscale
Energy kJ
969
1103
524
210
244
276
382
452
504
424
369
408
695
1000
2676
3607
2967
1024
487
885
295
Wind (km/h)
20
NW
30
SW
30
SSE
20
SSE
15
NNE
5
ENE
15
ENE
15
ENE
15
N
20
NE
20
ENE
15
NNE
30
NNE
30
NE
25
N
15
NW
15
WSW
5
S
0
NNE
5
SE
10
SW
Wind State
cross-off
cross-on
on
cross-on
off
glassy
cross-off
cross-off
off
cross-off
cross-off
off
cross-off
cross-off
off
cross-off
cross-on
on
glassy
cross-on
cross-on
High Tide
4:57PM1.35m
2:54AM1.44m
5:21PM1.37m
3:50AM1.49m
5:43PM1.38m
4:40AM1.50m
6:04PM1.38m
5:27AM1.47m
6:24PM1.39m
6:12AM1.40m
6:43PM1.39m
6:57AM1.29m
7:02PM1.40m
Low Tide
9:31AM0.04m
9:44PM0.99m
10:15AM0.00m
10:23PM0.88m
10:54AM0.03m
11:01PM0.75m
11:29AM0.11m
11:38PM0.63m
12:00PM0.24m
00:15AM0.53m
12:27PM0.38m
00:54AM0.46m
12:51PM0.53m
1:34AM0.43m
cloud
heavy rain
heavy rain
light rain
part cloud
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
clear
part cloud
clear
clear
clear
part cloud
rain showers
clear
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
4:54
4:54
4:56
4:56
4:56
4:58
4:58
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:31
6:30
6:30
6:29
6:28
6:27
6:25
 mm
38
51
5
6
1
1
1
2
2
5
2
1
Temp °C
25
23
22
24
24
24
27
27
25
27
28
26
27
27
24
28
28
26
28
27
26
Feels °C
24
21
20
24
25
26
28
29
27
28
30
29
26
25
23
29
29
30
34
31
31
  • 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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