Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 pm 01 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
26.8°C
0.2° 

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


Onjuku surf forecast from 1 Sep 2026:

  • Best quality surf: Tuesday 8 Sep, 9PM (local time) - 15ft (4.5m), 12s period, SSE swell with cross-onshore winds.
  • Most powerful swell: Tuesday 8 Sep, 9PM (local time) - 15ft (4.5m), 12s period, SSE swell with 4,949 kJ wave energy.
  • Next surfable swell (1★+): Thursday 3 Sep, 9PM (local time) - 2ft (0.6m), 10s 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 (Sep 03) at 9PM. The primary swell is predicted to be 0.6m and 10s period with a secondary swell of 0.9m and 6s. 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 4.5m 12s and forecast to arrive on Tuesday (Sep 08) 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 0.8m 4s period and expected on Friday (Sep 04) at 9PM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 9PM (Thu 3rd Sep)2ft (0.6m) 10s
Best Surf 9PM (Tue 8th Sep)15ft (4.5m) 12s
Most Powerful 9PM (Tue 8th Sep)15ft (4.5m) 12s

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


The Lowdown

Alright folks, Rusty here. Let’s have a look at what’s on the cards for Onjuku over the next couple of weeks.

To be straight with you, the first few days are a bit of a write-off. We’ve got some small waves on Wednesday, 2nd September, with an ESE breeze messing things up. Winds are light, but cross-on, and the swell is a weak 3 ft to 3 ft from the ESE with a short period of 10 seconds. The combined energy is low (205-275), so it’s just not worth paddling out for. Thursday and Friday are even worse – rain, onshore winds, and barely a ripple. Saturday and Sunday see a bit of a bump in size, but the wind is howling from the NE at 25 mph, so it’s messy and choppy. Best to leave the board in the car.

Then, on Monday morning, 7th September, things start to get interesting. The wind drops to a light breeze from the NE, swinging cross-offshore, and the wave height is a solid 6 ft from the E with a 7-second period. The combined energy jumps to 585 (moderate), and the wave comment says “expect very good surf conditions.” This is a standout window. The setup looks clean, but the period is short, so it might be a bit crumbly. Still, if you’re out there early, it could be worth it.

But hold onto your leash, because the real action is on Wednesday, 9th September. The swell is big – 13 ft in the morning, 12 ft in the afternoon – from the SSE with a period of 10-11 seconds, and the combined energy is through the roof (3822-5395). That’s strong wave energy. However, the wind is cross-on from the SSE to SE, so it’s going to be choppy. The file says the swell is too big for this break, so this is strictly for experts only. If you’re not comfortable in heavy, powerful surf, stay on the sand. The tide and wind are favorable in terms of direction, but the size is the limiting factor.

After that, the swell drops back but stays in the 7 ft to 8 ft range through to the 12th, with periods getting longer (12-13 seconds). The wind is light from the E to ESE, mostly cross-shore, so the waves will have some shape. The combined energy is still moderate to strong (1060-1483). The 12th of September looks like a decent option for intermediates, with clean conditions and a solid 7 ft from the SSE.

Into the second week, the swell hangs around 5 ft to 7 ft, but the wind picks up again from the ENE and ESE, making it lumpy. The 15th of September sees another big pulse from the SE – 12 ft with a 13-14 second period – but the wind is onshore from the S and SSE, so it’s messy and unknown quality. Only for the brave.

The 17th of September morning looks a bit better: 5 ft from the SE at 11 seconds, with a cross-offshore NE breeze at 16 mph. The combined energy is 1534 (strong), and the waves should be clean. A solid option for a session.

Bottom line: The standout is Monday morning, 7th September, for cleaner conditions if you can handle the short period. The big one on 9th September is for experts only. The 12th September afternoon is your best bet for a fun, manageable session with a bit of length to the swell.

This is Rusty, signing off. Keep your eyes on the horizon.

Short Range Forecast

Heavy rain (total 132mm), heaviest during Fri afternoon. Warm (max 28°C on Thu afternoon, min 21°C on Fri afternoon). Winds increasing (light winds from the SSE on Wed night, fresh winds from the ENE by Fri morning).

Days 5-7 Weather Summary

Heavy rain (total 181mm), heaviest during Sun night. Warm (max 28°C on Mon morning, min 19°C on Sat morning). Winds decreasing (strong winds from the NE on Sun morning, light winds from the NE by Mon morning).

Wednesday
2
Thursday
3
Friday
4
Saturday
5
Sunday
6
Monday
7
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
1
1
0
0
0
0
1
0
2
0
0
1
0
0
0
3
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)
0.9
ESE
11
0.9
ESE
10
1
E
10
0.6
E
11
0.7
E
10
0.6
E
10
0.6
E
10
0.8
SE
9
1
SE
8
0.8
SSW
9
1
ESE
7
1.1
ESE
6
1.3
ESE
7
1.7
E
7
1.6
ESE
7
1.7
E
7
1.7
E
7
2
S
12
2.3
SSE
12
Wave Graph
Metric surfscale
Energy kJ
210
146
200
88
98
71
68
95
108
118
105
108
158
315
261
306
311
1254
1413
Wind (km/h)
15
E
10
ESE
10
SE
5
SSE
10
SSW
15
SSW
20
NE
25
NE
20
NNE
25
NNE
35
NE
35
NNE
25
NNE
40
NE
40
NE
20
SSE
10
NE
35
SE
50
SE
Wind State
cross
cross-on
cross-on
on
on
on
cross-off
cross-off
cross-off
off
cross-off
cross-off
off
cross-off
cross-off
cross-on
cross-off
cross-on
cross-on
High Tide
7:30AM1.23m
6:53PM1.43m
8:31AM1.12m
7:17PM1.40m
10:14AM1.02m
7:46PM1.36m
8:26PM1.30m
4:09PM1.19m
10:16PM1.23m
3:44PM1.25m
00:42AM1.25m
Low Tide
1:09AM0.32m
12:52PM0.70m
1:54AM0.31m
1:12PM0.84m
2:52AM0.34m
1:18PM0.97m
4:13AM0.36m
6:01AM0.34m
6:12PM1.19m
7:30AM0.27m
8:17PM1.09m
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thunderstorm
thunderstorm
thunderstorm
heavy rain
heavy rain
light rain
mod rain
heavy rain
heavy rain
mod rain
heavy rain
thunderstorm
rain showers
thunderstorm
thunderstorm
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:11
5:11
5:11
5:13
5:13
5:13
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:06
6:05
6:04
6:01
6:00
5:59
5:58
 mm
2
1
4
5
43
77
3
7
24
27
8
32
68
5
7
13
Temp °C
25
27
27
26
27
28
26
23
21
21
22
20
21
22
24
25
28
27
28
Feels °C
26
30
29
29
31
31
30
21
21
19
19
16
18
19
22
24
29
27
26
  • 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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