Surf Forecasts:
Onjuku surf forecast from 3 Sep 2026:
- Best quality surf: Friday 4 Sep, 3AM (local time) - 1.5ft (0.5m), 9s period, E swell with cross-offshore winds.
- Most powerful swell: Tuesday 8 Sep, 9AM (local time) - 13ft (4.0m), 10s period, S swell with 3,643 kJ wave energy.
- Next surfable swell (1★+): Friday 4 Sep, 3AM (local time) - 1.5ft (0.5m), 9s 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 Friday (Sep 04) at 3AM. The primary swell is predicted to be 0.5m and 9s period with a secondary swell of 0.7m 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 4.0m 10s and forecast to arrive on Tuesday (Sep 08) at 9AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 5s period and expected on Thursday (Sep 10) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Fri 4th Sep) | 1.5ft (0.5m) 9s |
| Best Surf | 3AM (Fri 4th Sep) | 1.5ft (0.5m) 9s |
| Most Powerful | 9AM (Tue 8th Sep) | 13ft (4.0m) 10s |
Table - best surf conditions forecast for Onjuku over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s break down the Onjuku surf.
The next few days are flat out ugly. From Thursday (the 3rd) through Monday (the 7th), it’s all onshore wind and choppy junk. Rain and storms keep the surface a mess. There’s swell, but it’s short-period windswell around 6-8 seconds and blown out. A real blank stretch.
Things clean up around Saturday the 12th, but the first real session is Sunday the 13th morning. A 4ft SE swell with a light offshore breeze from the NE. The water temp is 79°, average for this time. Combined energy is moderate (353). It’s small but clean and rideable.
The standout is Monday the 14th afternoon. Onjuku gets glassy, dead calm winds, with a 4ft SE swell. Period is 9 seconds, the energy is moderate (381). This is your call for clean, lined-up waves for intermediates. Perfect conditions.
Tuesday the 15th morning is close behind – 4ft SE swell with offshore NE winds. Clean and groomed. Crowds are possible.
Wednesday the 16th morning looks very good with a 4ft SSE swell, light winds, and combined energy at 588 (moderate). That’s punchy and clean.
Looking further out, Thursday the 17th morning has a 5ft S swell with glassy conditions and an 11-second period – real groundswell. Energy hits 602 (moderate). It’s promising but more than a week away.
After that, it goes back to cross-onshore junk.
Bottom line: Best bet is Monday the 14th afternoon at Onjuku – glassy, 4ft SE swell, clean. Wednesday the 16th morning is a solid backup. Don’t miss it.
Rusty.
Short Range ForecastHeavy rain (total 87mm), heaviest during Fri night. Warm (max 29°C on Thu morning, min 21°C on Fri night). Winds increasing (light winds from the NE on Thu night, strong winds from the NNE by Sat night). | Days 4-6 Weather SummaryHeavy rain (total 120mm), heaviest during Sun night. Warm (max 28°C on Tue morning, min 24°C on Sun morning). Mainly near gales. | ||||||||||||||||||||
Thursday 3 | Friday 4 | Saturday 5 | Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | |||||||||||||||
AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | |
Swell Height Map |  |  |  |  |  |  |  | ||||||||||||||
Wave Height (m) Direction Period (s) | E 10 | E 10 | E 10 | S 10 | S 10 | S 9 | E 6 | E 6 | ENE 7 | ENE 7 | E 8 | E 9 | E 8 | ESE 9 | S 9 | S 10 | S 10 | S 10 | SSE 9 | SSE 9 | SSE 9 |
Wave Graph  | |||||||||||||||||||||
 kJ | 98 | 71 | 68 | 51 | 70 | 61 | 77 | 228 | 349 | 607 | 958 | 1225 | 762 | 708 | 1809 | 3643 | 2137 | 1618 | 1016 | 997 | 933 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross | on | on | cross-on | cross-on | on | on | on | on |
High Tide | 7:17PM1.40m | 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 | ||||||||||
Low Tide | 1:12PM0.84m | 2:52AM0.34m | 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 | |||||||||
 |  |  | | |  |  | |  | |  | | | |  | | | | | | | |
 | 5:11 | — | — | 5:11 | — | — | 5:13 | — | — | 5:13 | — | — | 5:13 | — | — | 5:15 | — | — | 5:16 | — | — |
 | — | 6:04 | — | — | 6:01 | — | — | 6:00 | — | — | 5:59 | — | — | 5:58 | — | — | 5:57 | — | — | 5:54 | — |
mm | 2 | 2 | 2 | 1 | 2 | 58 | 15 | 5 | — | 2 | 7 | 34 | 15 | 11 | 36 | 2 | 5 | 8 | 1 | 5 | 10 |
Temp °C | 29 | 29 | 23 | 24 | 24 | 23 | 22 | 23 | 23 | 24 | 24 | 24 | 27 | 27 | 27 | 28 | 28 | 27 | 28 | 28 | 27 |
Feels °C | 30 | 31 | 22 | 26 | 26 | 24 | 21 | 21 | 20 | 21 | 21 | 21 | 27 | 25 | 24 | 28 | 29 | 28 | 29 | 29 | 27 |
Swell 1 Height (m) Direction Period (s) | E 10 | E 10 | ENE 4 | SE 6 | SE 6 | S 9 | S 10 | SSW 9 | SSW 8 | SSW 9 | SW 9 | SSW 10 | E 8 | ESE 9 | E 9 | S 10 | SSE 10 | SSE 10 | E 9 | E 8 | ESE 16 |
| kJ | 98 | 71 | 18 | 40 | 32 | 61 | 47 | 28 | 24 | 7 | 13 | 10 | 762 | 708 | 262 | 2528 | 1495 | 1111 | 37 | 23 | 48 |
Swell 2 Height (m) Direction Period (s) | S 8 | SSW 8 | E 10 | S 10 | E 9 | E 9 | ESE 9 | ENE 13 | E 12 | SSE 8 | — | S 9 | SE 11 | E 18 | — | E 9 | E 9 | E 9 | E 17 | E 16 | NE 8 |
| kJ | 50 | 24 | 68 | 51 | 58 | 41 | 27 | 17 | 11 | 6 | — | 6 | 5 | 6 | — | 102 | 80 | 36 | 23 | 21 | 2 |
Swell 3 Height (m) Direction Period (s) | E 7 | E 6 | SE 6 | E 9 | S 10 | SE 7 | SE 9 | ENE 13 | SE 12 | SE 12 | — | — | SSW 9 | SW 9 | — | — | E 19 | E 18 | NNE 9 | NE 8 | — |
| kJ | 24 | 13 | 15 | 41 | 70 | 21 | 12 | 17 | 6 | 6 | — | — | 9 | 21 | — | — | 7 | 6 | 7 | 3 | — |
Wind waves Height (m) Direction Period (s) | SSW 9 | S 4 | — | NE 4 | — | NE 3 | E 6 | E 6 | ENE 7 | ENE 7 | E 8 | E 9 | — | — | S 9 | S 10 | S 10 | S 10 | SSE 9 | SSE 9 | SSE 9 |
| kJ | 80 | 15 | — | 9 | — | 2 | 77 | 228 | 349 | 607 | 958 | 1225 | — | — | 1809 | 3643 | 2137 | 1618 | 1016 | 997 | 933 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 23 | 135 | 9 | 0 | 0 | 40 | 51 | 617 | 575 | 295 | 536 | 617 | 56 | 57 | 295 | 101 | 143 | 617 | 557 | 557 | 101 |
Best forecast wave conditions in Chiba | |||||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||||
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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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