Avellanas Rivermouth Surf Forecast

/ Guanacaste (28 surf breaks) /

Costa Rica (96 surf breaks) / Lat Long: (10.24° N 85.84° W)

Surf Forecasts:

Avellanas Rivermouth surfForecast / Guanacaste / Costa Rica

12 Day Weather and Surf, issued 11 pm Monday 15 Sep 2025 CST

Forecast update in hr min s Forecast update imminent

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

Today's Avellanas Rivermouth sea temperature is 29.1° C
(Which is 1.0°C warmer than normal for this time of year)

Best Forecast Surf Conditions for Avellanas Rivermouth this week:

The surf forecast for Avellanas Rivermouth over the next 12 days: The first swell (rated 1 star or higher) is forecast to arrive on Tuesday (Sep 16) at 3AM. The primary swell is predicted to be 1.5m and 16s period with a secondary swell of 0.8m and 6s. The wind is predicted to be glassy as the swell arrives.

The most powerful waves expected at Avellanas Rivermouth in the next 12 days are 1.7m 16s and forecast to arrive on Tuesday (Sep 16) at 9AM. Winds are predicted to be glassy at the time the swell arrives.

Wave Type	Time (CST) & Date	Wave Height & Period
Next good surf (1 star+)	3AM (Tue 16th Sep)	5ft (1.5m) 16s
Best Surf	3AM (Tue 16th Sep)	5ft (1.5m) 16s
Most Powerful	9AM (Tue 16th Sep)	5.5ft (1.7m) 16s

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

Updates in hr min s Forecast update imminent

12 Days Hourly

Print Table

	Short Range Forecast Heavy rain (total 41mm), heaviest during Tue night. Warm (max 28°C on Tue morning, min 24°C on Wed night). Wind will be generally light.										Days 3-6 Weather Summary Moderate rain (total 17mm), heaviest on Thu night. Warm (max 28°C on Sun morning, min 25°C on Thu night). Wind will be generally light.
		Tuesday 16			Wednesday 17			Thursday 18			Friday 19			Saturday 20			Sunday 21			Mon 22
	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM	Night	AM	PM
Rating (10 max)	3	4	4	3	4	4	2	3	3	2	3	2	3	2	2	1	2	2	2	2	2
Swell Height Map See all maps
Wave Height (m) & direction (?)	SSW	SSW	SSW	SSW	SW	SW	SW	SW	SW	SSW	W	W	S	SW	SW	SW	SW	SW	SW	SW	SW
Period(s) (?)	16	16	15	15	15	15	14	14	14	14	8	8	13	13	13	12	15	14	13	13	13
Wave Graph (?)
Energy (?)	1312	1462	1117	1141	1153	1005	813	653	757	680	620	539	503	278	251	189	306	241	243	266	277
Wind (km/h)	E	SSE	SW	SE	SE	SSW	SSE	SSE	SSW	ESE	ESE	S	SSE	SSW	SW	WNW	WNW	W	WNW	NW	W
Wind State (?) onshore cross-onshore cross-shore cross-offshore offshore glassy	on	glass	glass	cross- on	glass	cross- off	cross- on	glass	cross- off	cross- on	glass	cross	glass	glass	cross- off	glass	off	off	off	cross- off	off
High Tide / height (m)		9:28AM 2.13		10:17PM 1.92	10:45AM 2.07		11:33PM 1.97	11:56AM 2.10		12:36AM 2.08		12:55PM 2.16	1:27AM 2.21		1:44PM 2.22	2:10AM 2.32		2:27PM 2.28	2:47AM 2.41		3:06PM 2.31
Low Tide / height (m)		3:06AM 0.61	4:01PM 0.54		4:25AM 0.67	5:14PM 0.55		5:41AM 0.64		6:18PM 0.49	6:44AM 0.56		7:11PM 0.42	7:36AM 0.46		7:55PM 0.36	8:21AM 0.37		8:35PM 0.31	9:00AM 0.29

		Tuesday 16			Wednesday 17			Thursday 18			Friday 19			Saturday 20			Sunday 21			Mon 22
Sunrise	-	5:33	-	-	5:31	-	-	5:31	-	-	5:31	-	-	5:31	-	-	5:31	-	-	5:31	-
Sunset	-	-	5:43	-	-	5:42	-	-	5:42	-	-	5:40	-	-	5:39	-	-	5:39	-	-	5:38

Rain (mm)	-	-	6	10	8	3	7	1	6	3	1	2	2	2	2	2	3	-	3	1	2
Temp. °C	26	28	28	27	28	26	24	26	26	25	26	26	25	27	27	26	28	27	26	28	28
Feels °C (?)	29	32	33	31	32	29	27	30	28	29	31	30	29	32	30	31	31	29	30	31	31

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 Guanacaste

Wind Update Continuing clean conditions at Avellanas Rivermouth (calm at Liberia/Tomas Guardia Airport 51 km from Avellanas Rivermouth). 1.1m 16s long period groundswell from the SW with a 0.7m 6s windswell from the SSW and a 0.6m 12s groundswell from the SW. 3 swells combining to make bigger set waves.
3 hours 15 minutes ago Avellanas Rivermouth

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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 Avellanas Rivermouth 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 Avellanas Rivermouth Surf forecast

The above surf forecast table for Avellanas Rivermouth provides essential information for determining whether the surfing conditions will be good over the next 12 days. A general guide to surfing at Avellanas Rivermouth can be found by selecting the local surf guide option on the grey menu. Our Avellanas Rivermouth 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 (Avellanas Rivermouth) 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 Avellanas Rivermouth 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.

Avellanas Rivermouth is 44 km (27 miles) from Nicoya. If you plan a holiday in Guanacaste, look for hotels and other accommodation in Nicoya. Nicoya has rooms for a wide range of budgets as well as car hire and transport links.