Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 am 23 Aug 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
27.3°C
0.5° 

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, 6PM (local time) - 6.5ft (2.0m), 15s period, SSE swell with 1,714 kJ wave energy.
  • Next surfable swell (1★+): Sunday 23 Aug, 6PM (local time) - 2.5ft (0.7m), 12s 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 Sunday (Aug 23) at 6PM. The primary swell is predicted to be 0.7m and 12s period with a secondary swell of 0.7m and 9s. 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 2.0m 15s and forecast to arrive on Monday (Aug 24) at 6PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.3m 3s period and expected on Sunday (Aug 23) at 3PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 6PM (Sun 23rd Aug)2.5ft (0.7m) 12s
Best Surf 6AM (Mon 24th Aug)2.5ft (0.8m) 18s
Most Powerful 6PM (Mon 24th Aug)6.5ft (2.0m) 15s

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


The Lowdown

Alright, Rusty here with the imperial rundown.

Right now we’re in a flat spell at Onjuku. Small surf and just ordinary conditions. We start on Sunday the 23rd of August with tiny 2ft easterly swell, period around 9 seconds, so it’s weak and mushy. Wind is a light cross-offshore from the NE, surface is clean, but there’s barely any energy (combined energy of all swells directed here is 102). It’s surfable but very ordinary. Water temp is 81°, about average for this time of year.

Sunday afternoon stays small at 2ft from the SSE, period jumps to 12 seconds, wind goes cross-shore, energy picks up to 241. Still marginal.

Monday the 24th sees a bump. Morning has 3ft from the SSE with a very long period of 18 seconds – proper groundswell – energy at 941. Wind is light southerly and onshore, so it’s clean but questionable on the tide. Afternoon gets bigger at 6ft, same SSE direction, period 16 seconds, energy 1827, but wind swings cross-onshore from the SSW at 12 mph, making it choppy.

From Tuesday the 25th through Thursday the 27th, conditions get worse. Swell hangs around 2ft to 6ft but winds are cross-onshore and fresh, blowing the surface out. Thursday even has a risk of thunderstorms. Rough patch.

Friday the 28th is small and marginal with light rain and cross-onshore wind.

Saturday the 29th and Sunday the 30th clean up a bit. Swell stays tiny, 2ft to 3ft, but wind goes cross-offshore from the ENE, so the surface is glassy. Energy is low (148 to 259), so it’s more about a gentle paddle.

Now the good stuff. Monday the 31st of August morning and afternoon both look good. Swell is small at 2ft from the east, period 11 seconds, but the wind goes offshore from the north at just 6 mph – glassy conditions. Energy is moderate (227) and the reports say to expect good surf. Clean and inviting.

The standout is Tuesday the 1st of September. Morning has 4ft southerly swell with a 14-second period, energy at 838. By the afternoon, it’s 5ft from the south, period 13 seconds, energy 881, and the wind is offshore from the NNE at 12 mph – that’s clean, lined-up waves. This is the best of the whole outlook. The swell direction from the south matches the optimum SSE well.

Wednesday the 2nd of September sees a bump – 6ft to 6ft from the ESE, period 10 seconds, energy hits 1801 in the afternoon. Wind is cross-offshore from the NE, so it’s clean, but shorter period makes it more of a beach-blast.

From Thursday the 3rd onward, conditions become uncertain. Winds pick up, and by the 4th and 5th of September we’re looking at strong onshore winds and building chop, with swell up to 8ft from the SE – expert-only and blown out. The final days, 6th and 7th of September, are a write-off.

Best bet: Monday the 31st for small, clean fun, and absolutely Tuesday the 1st of September for the standout session. Don’t miss that Tuesday afternoon.

Rusty.

Short Range Forecast

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

Days 4-6 Weather Summary

Moderate rain (total 19mm), heaviest on Thu night. Warm (max 29°C on Wed morning, min 23°C on Fri morning). Winds decreasing (fresh winds from the SSW on Wed afternoon, calm by Fri night).

Sunday
23
Monday
24
Tuesday
25
Wednesday
26
Thursday
27
Friday
28
Saturday
29
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
1
2
2
1
0
0
0
0
0
0
0
0
0
0
1
0
2
1
1
1
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.7
E
9
0.6
SSE
12
0.8
SSE
12
0.9
SSE
18
1.8
SSE
16
1.7
SSE
13
1.8
SSE
13
1.7
SSE
13
1.5
S
12
0.9
S
12
0.9
SSW
13
0.8
SSW
12
1.1
S
10
0.7
E
13
0.7
E
13
0.7
E
12
0.7
E
12
0.8
S
10
0.8
SSW
10
0.7
S
10
0.6
E
11
Wave Graph
Metric surfscale
Energy kJ
83
104
196
459
1634
960
1094
980
661
228
277
169
225
173
163
148
137
117
131
91
85
Wind (km/h)
10
NE
10
E
5
N
5
S
20
SSW
20
SW
25
SW
25
SSW
25
SW
25
SW
30
SSW
30
SW
25
SSW
20
SSW
20
SW
10
WSW
20
WSW
0
W
20
ENE
20
ENE
15
NE
Wind State
cross-off
cross
glassy
on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
glassy
cross-off
cross-off
cross-off
High Tide
4:31PM1.15m
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
7:50PM1.12m
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
part cloud
clear
clear
clear
clear
part cloud
part cloud
part cloud
clear
clear
rain showers
thunderstorm
thunderstorm
thunderstorm
light rain
clear
thunderstorm
thunderstorm
light rain
rain showers
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:03
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
1
2
1
8
5
2
1
1
5
Temp °C
27
27
25
28
28
26
29
28
27
29
29
27
27
28
27
25
27
25
26
26
25
Feels °C
29
30
30
31
29
28
30
28
29
30
30
27
28
30
29
26
28
28
27
27
27
  • 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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