Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 am 04 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
26.1°C
0.4° 

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


Onjuku surf forecast from 4 Sep 2026:

  • Best quality surf: Tuesday 8 Sep, 9AM (local time) - 11ft (3.5m), 10s period, S swell with cross-onshore winds.
  • Most powerful swell: Monday 7 Sep, 12PM (local time) - 15ft (4.5m), 11s period, S swell with 4,181 kJ wave energy.
  • Next surfable swell (1★+): Tuesday 8 Sep, 9AM (local time) - 11ft (3.5m), 10s 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 Tuesday (Sep 08) at 9AM. The primary swell is predicted to be 3.5m and 10s period with a secondary swell of 3.0m and 10s. Another secondary swell of 0.7m and 9s is also forecast. The wind is predicted to be cross-onshore as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 4.5m 11s and forecast to arrive on Monday (Sep 07) at 12PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.6m 6s period and expected on Saturday (Sep 05) at 9AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 9AM (Tue 8th Sep)11ft (3.5m) 10s
Best Surf 9AM (Tue 8th Sep)11ft (3.5m) 10s
Most Powerful12PM (Mon 7th Sep)15ft (4.5m) 11s

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


The Lowdown

G'day, Rusty here.

Look, if you’re hanging for a surf at Onjuku over the next sixteen days, you’re going to need a whole lot of patience. The first week is pretty much a write-off, and it’s not until we get into the second week that things start to look a little more interesting.

Right now, the surf is flat and messy. We’ve got a run of poor conditions from today through to late next week. The water temp is sitting around 79°, which is about average for this time of year, so at least you won’t need a thick wetsuit when you finally paddle out.

The first real chance of a wave comes on Tuesday the 8th of September. The morning is a write-off with a big, stormy 12ft to 13ft swell from the SSE and strong SSW winds – that’s way too much grunt for a spot like Onjuku, and it’s only for experts. But hold onto your leash, because Tuesday afternoon sees a shift: the wind drops to glassy – yes, glassy – with a lighter NE breeze at just 3 mph. The swell drops to a still-chunky 10ft from the SSE, with a solid 10-second period and strong wave energy (1630). This is excellent for experienced surfers. That long-period groundswell at a beach break can be a bit straight, so the shape might be a little walled, but when it’s glassy like that and you’ve got that much push, it’s a standout session for the crew who know what they’re doing. Expect crowds likely here, as it’s the only proper window.

After that, we slide back into small, weak surf – 1ft to 3ft with short periods – and cross-off or onshore winds through to the middle of the month. There’s a long gap of nothing special until Wednesday the 16th of September. Wednesday afternoon sees a clean 8ft swell from the ENE with a 9-second period and moderate wave energy (1834). The wind is a solid cross-off from the NE at 22 mph, which will keep the surface clean, but that’s a strong breeze. The consistency is marginal, and the size is pushing into expert territory at over 8ft. It’s a promising option for the brave, but a long way out.

Even later, Thursday the 17th and Friday the 18th of September offer cleaner, more manageable 6ft to 8ft swells from the ENE and E, with cross-off winds. The wave energy drops back to moderate (around 500-800), so it’s more surfable for intermediate surfers, but not a standout. The period is short (7-9 seconds), so the waves will be a bit weaker and more crumbly.

So, the best on offer? Hands down, it’s Tuesday the 8th of September afternoon – glassy, 10ft SSE groundswell for the experienced. After that, keep an eye on the second week, but the quality is marginal for most. Onjuku is inconsistent, and this is a classic blank run for the area – it tends not to stay poor forever, but you’ve got to wait for it.

Rusty.

Short Range Forecast

Heavy rain (total 271mm), heaviest during Sun night. Warm (max 26°C on Fri morning, min 20°C on Sat afternoon). Winds increasing (light winds from the ENE on Fri morning, near gales from the E by Sun night).

Days 4-6 Weather Summary

Heavy rain (total 94mm), heaviest during Mon morning. Warm (max 28°C on Tue morning, min 21°C on Wed night). Winds decreasing (fresh winds from the SSW on Mon night, calm by Tue night).

Friday
4
Saturday
5
Sunday
6
Monday
7
Tuesday
8
Wednesday
9
Thursday
10
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
0
!
4
3
0
1
0
0
0
1
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.6
S
10
0.6
S
10
0.6
S
9
0.5
S
10
1.5
E
7
0.2
E
12
2
ENE
7
2.5
E
8
3
E
8
4
SE
10
3.5
SSE
11
3
S
11
3.5
S
10
3
SSE
10
2.4
SSE
11
2
SSE
10
1.6
SSE
9
1.3
SSE
9
0.9
S
8
0.4
ESE
14
1.3
E
6
Wave Graph
Metric surfscale
Energy kJ
73
70
61
47
193
14
360
926
1379
2777
2671
2444
2180
1587
1221
712
451
276
113
70
130
Wind (km/h)
15
ENE
15
NE
20
NE
30
ENE
35
NNE
35
NNE
40
NE
30
E
45
E
25
SSW
30
SSW
35
SSW
20
SSW
5
NE
10
S
20
SW
10
WSW
35
NE
35
NE
30
NE
25
NE
Wind State
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross-off
cross
on
on
cross-on
cross-on
glassy
on
cross-on
cross-on
cross-off
cross-off
cross-off
cross-off
High Tide
10:14AM1.02m
7:46PM1.36m
8:26PM1.30m
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
Low Tide
1:18PM0.97m
4:13AM0.36m
6:01AM0.34m
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
part cloud
thunderstorm
thunderstorm
heavy rain
light rain
light rain
heavy rain
heavy rain
heavy rain
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
rain showers
mod rain
thunderstorm
heavy rain
light rain
light rain
light rain
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:11
5:13
5:13
5:13
5:15
5:16
5:16
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:01
6:00
5:59
5:58
5:57
5:54
5:53
 mm
2
16
22
4
3
14
36
174
46
6
1
4
4
12
6
3
12
3
2
2
Temp °C
26
25
24
22
21
21
23
24
26
26
27
27
28
25
26
27
27
24
21
21
21
Feels °C
28
27
25
20
18
17
20
23
23
27
28
27
31
29
30
29
31
24
18
18
19
  • 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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