Onjuku Surf Break

Lat Long: 35.18° N 140.35° E

Onjuku Surf Forecast and Surf Report

Issued: 8 am 14 Sep 2026 (local time)

Forecast update in  hr  min

Today's Onjuku sea temperature is
26.1°C
0.0° 

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


Onjuku surf forecast from 14 Sep 2026:

  • Best quality surf: Saturday 19 Sep, 9AM (local time) - 11ft (3.5m), 14s period, SE swell with offshore winds.
  • Most powerful swell: Monday 21 Sep, 3PM (local time) - 13ft (4.0m), 15s period, S swell with 6,892 kJ wave energy.
  • Next surfable swell (1★+): Tuesday 15 Sep, 9PM (local time) - 2.5ft (0.7m), 13s 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 Tuesday (Sep 15) at 9PM. The primary swell is predicted to be 0.7m and 13s period with a secondary swell of 1.1m and 8s. Another secondary swell of 1.2m and 7s is also forecast. The wind is predicted to be glassy as the swell arrives.

The most powerful waves expected at Onjuku in the next 16 days are 4.0m 15s and forecast to arrive on Monday (Sep 21) at 3PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.6m 6s period and expected on Monday (Sep 21) at 6AM.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 9PM (Tue 15th Sep)2.5ft (0.7m) 13s
Best Surf 9AM (Sat 19th Sep)11ft (3.5m) 14s
Most Powerful 3PM (Mon 21st Sep)13ft (4.0m) 15s

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


The Lowdown

Howdy, Rusty here. Let’s break down what’s cooking at Onjuku over the next couple weeks.

First off, you’re looking at a pretty bleak start. From now through Wednesday the 18th, it’s mostly poor – choppy, cross-onshore breezes and messy surf with waves running 2 to 6 feet from the SSE and E. Tuesday afternoon has a window where the wind drops to 3 mph and goes onshore, but it’s still only marginal. Wednesday morning sees a cross-offshore wind from the NE at 16 mph, keeping things clean, but the swell is only 3 feet and tide or something is off. Not worth it.

Then things get interesting. Thursday the 19th brings a big pulse – offshore winds from the NNE at 19 mph, huge 12-foot swell from the SE with a period of 14 seconds. That’s a proper groundswell, very long period, with a combined energy of 4657 (strong) in the morning and 4991 (strong) in the afternoon. But here’s the catch – this is too big for Onjuku. It’s a beach break, and that size will be heavy. Only for experts, and even then it’s risky. Saturday the 20th stays similar – 10 to 12 feet, offshore winds, clean faces, but massive energy (3168–4962). Sunday the 21st takes it even higher – 12 to 13 feet from S and SSE, periods up to 15 seconds and energy readings into the 8182 range (very strong). That’s some of the strongest energy around, but again, it’s too much for this spot.

The standout is Tuesday the 22nd. Morning has an 8-foot swell from the ENE, offshore NNE wind at 16 mph, making for moderate offshore and clean conditions. Combined energy is 2240 (strong) – still solid but not stupid. Afternoon drops to 7 feet, energy 1094 (moderate). Winds stay offshore in the light to moderate breeze range. Swell period is 10–11 seconds – decent. This is the best on offer: clean, manageable size for experienced surfers, and a good session.

Wednesday the 23rd goes downhill fast – onshore winds from S and SSW at 19–25 mph, rain and thunderstorms, poor. Thursday the 24th has a tiny window – glassy morning with 3 feet of ENE swell and no wind, but it’s ordinary and small. After that, it’s mostly poor surf with tiny 2 to 3-foot waves and messy winds straight through to the end of the month.

Water temp is 79°, which is about average for this time of year.

So bottom line: the best is Tuesday the 22nd at Onjuku. That morning with offshore wind and solid 8-foot swell is your best bet. The Thursday and Friday before are just too big for this break, and the rest is small and messy. If you’re an expert looking for a heavy paddle, the 19th and 20th might get your heart going, but it’s a gamble.

Keep it between the buoys.

Rusty.

Short Range Forecast

Heavy rain (total 88mm), heaviest during Wed night. Warm (max 27°C on Mon morning, min 20°C on Wed night). Winds increasing (calm on Tue night, fresh winds from the N by Wed night).

Days 4-6 Weather Summary

Moderate rain (total 19mm), heaviest on Sat night. Warm (max 22°C on Thu morning, min 20°C on Thu night). Winds decreasing (strong winds from the NNE on Fri afternoon, light winds from the NNE by Sat night).

Monday
14
Tuesday
15
Wednesday
16
Thursday
17
Friday
18
Saturday
19
Sunday
20
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
1
2
1
0
0
0
0
1
1
1
5
!
!
!
4
!
4
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
SSE
10
0.9
SE
9
1.2
SE
9
0.7
E
14
0.8
E
14
0.7
E
13
0.8
E
13
0.7
E
12
1.4
NE
6
1.8
ENE
7
2
ENE
8
2.1
ENE
8
2.5
ENE
8
1.4
SE
15
3
SE
15
3.5
SE
14
3.5
SE
13
4
SE
12
3
SE
12
3.5
SE
13
2.5
S
14
Wave Graph
Metric surfscale
Energy kJ
85
147
231
195
261
167
215
148
157
316
428
494
798
891
4357
4135
4554
4562
3116
3816
2521
Wind (km/h)
25
SSW
25
SSW
25
SW
15
SSW
5
S
5
WNW
25
NE
25
NE
35
N
35
NNE
35
NNE
35
NNE
40
NNE
40
NNE
35
NNE
30
NNE
30
NNE
20
NNE
30
NNE
30
NNE
30
N
Wind State
cross-on
cross-on
cross-on
cross-on
on
glassy
cross-off
cross-off
off
cross-off
cross-off
cross-off
off
cross-off
off
off
off
cross-off
off
off
off
High Tide
5:44PM1.44m
6:45AM1.29m
6:03PM1.43m
7:26AM1.19m
6:22PM1.41m
8:14AM1.09m
6:42PM1.37m
9:27AM0.99m
7:03PM1.31m
7:24PM1.24m
7:46PM1.15m
Low Tide
11:50AM0.57m
00:19AM0.26m
12:11PM0.69m
00:53AM0.27m
12:28PM0.79m
1:31AM0.32m
12:40PM0.87m
2:15AM0.40m
12:34PM0.94m
3:18AM0.48m
5:00AM0.52m
clear
clear
rain showers
rain showers
mod rain
mod rain
mod rain
heavy rain
thunderstorm
cloud
part cloud
cloud
cloud
cloud
cloud
light rain
mod rain
heavy rain
light rain
cloud
light rain
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:18
5:20
5:20
5:22
5:22
5:22
5:24
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
5:47
5:46
5:45
5:44
5:42
5:40
5:38
 mm
2
8
9
7
10
14
38
1
7
11
3
1
Temp °C
27
26
26
24
24
25
22
23
23
22
22
21
21
21
21
22
22
22
22
23
22
Feels °C
28
26
27
25
28
30
22
23
25
18
18
16
16
16
18
20
21
22
21
21
21
  • 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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