Onjuku Surf Forecast

/ Chiba (19 surf breaks) /

Japan (129 surf breaks) / Lat Long: (35.18° N 140.35° E)

Surf Forecasts:

Onjuku surfForecast / Chiba / Japan

12 Day Weather and Surf, issued 8 pm Wednesday 20 Aug 2025 JST

Forecast update in hr min s Forecast update imminent

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

Today's Onjuku sea temperature is 26.5° C
(Which is normal for this time of year)

Best Forecast Surf Conditions for Onjuku this week:

The surf forecast for Onjuku over the next 12 days: The first swell (rated 1 star or higher) is forecast to arrive on Friday (Aug 22) at 12AM. The primary swell is predicted to be 0.3m and 12s period with a secondary swell of 0.4m and 5s. Another secondary swell of 0.3m and 9s is also forecast. The wind is predicted to be glassy as the swell arrives.

The most powerful waves expected at Onjuku in the next 12 days are 1.4m 6s and forecast to arrive on Wednesday (Aug 27) at 12AM. Winds are predicted to be cross-onshore at the time the swell arrives.

Wave Type	Time (JST) & Date	Wave Height & Period
Next good surf (1 star+)	12AM (Fri 22nd Aug)	1ft (0.3m) 12s
Best Surf	12AM (Fri 22nd Aug)	1ft (0.3m) 12s
Most Powerful	12AM (Wed 27th Aug)	4.5ft (1.4m) 6s

Table - best surf conditions forecast for Onjuku over the next 12 days.

Updates in hr min s Forecast update imminent

12 Days Hourly

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	Short Range Forecast Mostly dry. Warm (max 30°C on Thu morning, min 26°C on Wed night). Winds decreasing (fresh winds from the SW on Wed night, calm by Fri night).										Days 3-6 Weather Summary Mostly dry. Warm (max 30°C on Sun morning, min 25°C on Sat night). Winds increasing (calm on Mon morning, fresh winds from the SSW by Tue afternoon).
		Thursday 21			Friday 22			Saturday 23			Sunday 24			Monday 25			Tuesday 26			Wed 27
	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM
Rating (10 max)	0	0	0	1	1	0	1	1	0	0	0	0	0	1	0	0	0	0	0	0	0
Swell Height Map See all maps
Wave Height (m) & direction (?)	SSW	SW	SW	SE	SE	SE	SE	SE	SE	ESE	ESE	ESE	ESE	ESE	ESE	SE	SSW	SSW	SSW	SSW	SSW
Period(s) (?)	5	5	5	12	12	10	9	9	9	8	8	8	8	8	8	8	5	5	6	6	6
Wave Graph (?)
Energy (?)	91	114	74	46	46	54	43	49	43	37	39	52	39	49	48	34	70	136	174	111	140
Wind (km/h)	SW	WSW	SSW	WNW	ENE	ESE	WNW	SE	SSW	SW	SW	SSW	SW	S	SSW	SSW	SW	SW	SW	SW	SW
Wind State (?) onshore cross-onshore cross-shore cross-offshore offshore glassy	cross- on	cross- on	on	glass	cross- off	cross	glass	glass	on	cross- on	cross- on	cross- on	cross- on	glass	on	cross- on	cross- on	cross- on	cross- on	cross- on	cross- on
High Tide / height (m)	1:41AM 1.32		4:46PM 1.30	2:48AM 1.38		5:04PM 1.32		3:39AM 1.43	5:22PM 1.34		4:24AM 1.45	5:40PM 1.35		5:05AM 1.44	5:57PM 1.37		5:44AM 1.40		6:13PM 1.38	6:23AM 1.33
Low Tide / height (m)		9:23AM 0.14		9:36PM 0.97	10:03AM 0.11		10:11PM 0.85	10:38AM 0.13		10:43PM 0.73	11:08AM 0.19		11:15PM 0.62	11:36AM 0.28		11:47PM 0.53	12:00PM 0.38		12:19AM 0.46		12:23PM 0.50

		Thursday 21			Friday 22			Saturday 23			Sunday 24			Monday 25			Tuesday 26			Wed 27
Sunrise	-	5:01	-	-	5:01	-	-	5:03	-	-	5:03	-	-	5:05	-	-	5:05	-	-	5:05	-
Sunset	-	-	6:21	-	-	6:19	-	-	6:17	-	-	6:16	-	-	6:15	-	-	6:14	-	-	6:13

Rain (mm)	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Temp. °C	27	30	29	27	29	29	27	29	29	26	30	29	26	29	28	26	29	28	27	29	30
Feels °C (?)	28	33	32	32	33	32	32	32	31	29	32	31	29	32	30	29	28	27	26	29	30

Map Icons:
Break
Live Wave Height (m)
Live Wind Speed (km/h)
Surf Rating (10 Max)
Ocean Swells (m)
Wind Speed (km/h)

Recent Eyeball Surf Reports for Chiba

Wind Update Continuing clean conditions at Onjuku (light winds from the WNW at Katsuura 5 km from Onjuku). 1.1m 5s windswell from the SSW with a 0.4m 10s swell from the E. 2 swells combining to make bigger set waves.
1 hour 17 minutes ago Onjuku

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1 h 17 min ago

6 km/h

WNW

Clean

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The surf report / weather widget below is available to embed on third party websites free of charge and provides a summary of our Onjuku surf forecast. Simply grab the html code snippet that we provide and paste it into your own site. You can choose your preferred language and metric/imperial units for the surf forecast feed to suit users of your site. Click here to get the code.

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 12 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.