Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 2 am 06 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
27.9°C
1.4° 

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


Onjuku surf forecast from 5 Sep 2026:

  • Best quality surf: Wednesday 9 Sep, 9PM (local time) - 5.5ft (1.7m), 9s period, S swell with offshore winds.
  • Most powerful swell: Monday 7 Sep, 9PM (local time) - 10ft (3.0m), 9s period, S swell with 1,672 kJ wave energy.
  • Next surfable swell (1★+): Wednesday 9 Sep, 9PM (local time) - 5.5ft (1.7m), 9s period with S 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 (Sep 09) at 9PM. The primary swell is predicted to be 1.7m and 9s period with a secondary swell of 0.3m and 16s. Another secondary swell of 1.6m and 6s is also forecast. The wind is predicted to be offshore as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 3.0m 9s and forecast to arrive on Monday (Sep 07) at 9PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.5m 6s period and expected on Sunday (Sep 06) at 6AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 9PM (Wed 9th Sep)5.5ft (1.7m) 9s
Best Surf 9PM (Wed 9th Sep)5.5ft (1.7m) 9s
Most Powerful 9PM (Mon 7th Sep)10ft (3.0m) 9s

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


The Lowdown

Alright folks, Rusty here. Let's get into it for our local stretch of coast. We've got a pretty ordinary run of surf ahead, with a lot of wind-affected, messy swell to sit through before we see any real quality.

Things kick off with a pulse of easterly windswell, but it's a write-off. Sunday the 6th sees 6ft of short-period, 6-second junk from the east, blown out by a 19 mph ENE cross-off. The combined energy is weak (272), and it's just poor. This mess gets worse into Monday the 7th as a 10ft southerly swell arrives, but it's accompanied by 28 mph onshore winds, making it a total washout.

The whole first week is a bust. Onshore winds and lumpy conditions dominate from Tuesday the 8th through to Thursday the 10th. Swell hangs around the 5ft to 7ft mark, but the wind just won't play ball. The water is a touch warmer than normal for this time of year at 82°F.

We finally get a breath of fresh air on Friday the 11th. A tiny 2ft groundswell from the east rolls in with a very long 14-second period. The wind goes glassy in the morning, a real treat. The combined energy is still weak (209), but that clean, glassy surface will make it feel better than it looks. It's a very small wave, but it's the cleanest we've seen.

Saturday the 12th and Sunday the 13th see the same tiny east swell, but the wind swings back to a 12 mph cross-off, keeping it clean but small. The energy ticks up a little (336), but we're still looking at waist-high dribblers at best.

The real standout appears around Monday the 14th. A new 6ft east swell fills in, with a moderate 10-second period. The combined energy jumps to a solid moderate (815). The wind is a fresh 19 mph cross-off, which will keep the surface clean. This is the best size and energy we've seen in the whole outlook.

Tuesday the 15th is a close second. We've got a 4ft east swell with a 9 mph offshore wind in the morning. That's a clean, offshore setup with moderate energy (443). It's a proper session if you can get out.

By Wednesday the 16th, the swell fades fast, and the onshore junk returns. The rest of the run into the 18th is a mix of tiny, clean little waves from the east and the occasional short-period windswell slop. The final day, Monday the 21st, offers a surprise 5ft south-southwest swell with a clean cross-off. It's a late-period option with moderate energy (324), but it's a long way out.

Overall, the best bet is Monday the 14th at Onjuku. The 6ft east swell combined with a clean cross-off wind gives you the most push and the best chance of a decent wave. It's inconsistent, so you'll have to be patient, but it's the one to circle. The 11th offers the cleanest conditions, but it's tiny. Tuesday the 15th is the other highlight with offshore winds and a clean, manageable swell.

Rusty out.

Short Range Forecast

Heavy rain (total 154mm), heaviest during Sun afternoon. Warm (max 27°C on Mon morning, min 22°C on Sun morning). Winds decreasing (strong winds from the S on Mon afternoon, light winds from the SW by Tue morning).

Days 4-6 Weather Summary

Light rain (total 4mm), mostly falling on Wed afternoon. Warm (max 28°C on Wed morning, min 21°C on Wed night). Wind will be generally light.

Sunday
6
Monday
7
Tuesday
8
Wednesday
9
Thursday
10
Friday
11
Saturday
12
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
1
0
0
0
2
0
0
2
2
1
0
0
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)
1.8
E
6
2.2
E
7
2.4
ESE
8
3
SE
8
3
S
9
2.3
S
9
2
S
9
1.8
SSE
9
2
S
9
2
S
9
2.5
SSW
9
1.6
S
9
1.4
S
8
1.2
S
8
1
S
8
0.5
E
14
0.5
E
14
0.6
E
14
0.6
E
14
0.6
E
14
0.6
E
14
Wave Graph
Metric surfscale
Energy kJ
255
439
672
1003
1487
904
675
540
670
607
929
398
279
190
125
106
100
136
134
132
132
Wind (km/h)
30
ENE
40
NE
35
ESE
40
SSE
45
S
30
SW
20
SW
10
SSW
25
SSW
30
SW
25
SW
25
N
10
WSW
20
SSW
15
NE
5
NNE
15
NE
15
NE
15
NE
20
NE
10
NNE
Wind State
cross-off
cross-off
cross-on
cross-on
on
cross-on
cross-on
cross-on
cross-on
cross-on
cross-on
off
cross-on
cross-on
cross-off
glassy
cross-off
cross-off
cross-off
cross-off
cross-off
High Tide
4:09PM1.19m
10:16PM1.23m
3:44PM1.25m
00:42AM1.25m
3:57PM1.30m
2:06AM1.33m
4:14PM1.34m
3:06AM1.40m
4:32PM1.36m
3:56AM1.45m
4:50PM1.39m
4:41AM1.47m
5:08PM1.41m
Low Tide
6:12PM1.19m
7:30AM0.27m
8:17PM1.09m
8:30AM0.20m
8:59PM0.95m
9:17AM0.17m
9:34PM0.80m
9:55AM0.18m
10:07PM0.64m
10:29AM0.24m
10:40PM0.50m
10:59AM0.34m
11:13PM0.38m
light rain
heavy rain
thunderstorm
thunderstorm
mod rain
thunderstorm
thunderstorm
thunderstorm
thunderstorm
part cloud
thunderstorm
light rain
part cloud
part cloud
part cloud
cloud
cloud
part cloud
part cloud
part cloud
part cloud
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:13
5:13
5:15
5:16
5:16
5:16
5:18
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
5:59
5:58
5:57
5:54
5:53
5:52
5:51
 mm
5
49
63
13
7
5
3
3
6
2
2
Temp °C
23
23
26
27
27
26
27
27
27
28
28
23
25
27
23
24
23
22
24
24
23
Feels °C
20
21
26
26
25
27
30
31
30
29
29
24
25
31
25
28
25
23
26
25
25
  • 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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