Avellanas Rivermouth surfForecast / Guanacaste / Costa Rica

information circle12 Day Weather and Surf, issued 11 am Sunday 28 Dec 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
28.3° C
(Which is 1.2°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 Sunday (Dec 28) at 6PM. The primary swell is predicted to be 0.4m and 15s period with a secondary swell of 0.5m and 6s. The wind is predicted to be cross-offshore as the swell arrives.

The most powerful waves expected at Avellanas Rivermouth in the next 12 days are 0.6m 12s and forecast to arrive on Wednesday (Dec 31) at 3PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.5m 4s period and expected on Saturday (Jan 03) at 12AM.

Wave TypeTime (CST) & Date Wave Height & Period
Next good surf (1 star+) 6PM (Sun 28th Dec)1.5ft (0.4m) 15s
Best Surf 6PM (Sun 28th Dec)1.5ft (0.4m) 15s
Most Powerful 3PM (Wed 31st Dec)2ft (0.6m) 12s

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

Updates in  hr  min  s Forecast update imminent

Short Range Forecast Mostly dry. Warm (max 30°C on Sun morning, min 23°C on Sun night). Winds increasing (calm on Sun afternoon, fresh winds from the ENE by Tue afternoon).

Days 3-6 Weather Summary Mostly dry. Warm (max 30°C on Wed afternoon, min 22°C on Wed night). Winds decreasing (fresh winds from the ENE on Wed night, calm by Fri afternoon).

Sunday
28
Monday
29
Tuesday
30
Wednesday
31
Thursday
01
Friday
02
Saturday
03
AMPMNightAMPMNightAMPMNightAMPMNightAMPMNightAMPMNightAMPMNight
Rating
(10 max)
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
Swell
Height Map
Wave Height (m) & direction (?)
0.4
SW
0.4
SW
0.4
SW
0.4
SW
0.4
SW
0.4
SW
0.4
SW
0.4
SW
0.5
S
0.4
S
0.6
S
0.6
S
0.6
S
0.4
SSW
0.4
SSW
0.6
S
0.6
S
0.5
S
0.6
S
0.3
S
0.4
SSW
Period(s) (?)151514131313131213111212121111111111101211
Wave
Graph
(?)Metric surfscale
Energy kJ (?)757570456261403884371101021024340858455722740
Wind
(km/h)
25
ENE
0
SE
15
E
20
NE
5
NNE
20
ENE
25
NE
25
NE
25
ENE
25
ENE
25
NE
20
ENE
25
NE
20
NE
20
ENE
20
ENE
5
N
15
E
15
ENE
10
W
5
ESE
Wind State (?)
onshore
cross-onshore
cross-shore
cross-offshore
offshore
glassy
onglassoncross-
on
glasscross-
on
cross-
on
cross-
on
cross-
on
cross-
on
cross-
on
cross-
on
cross-
on
cross-
on
oncross-
on
glassoncross-
on
offon
High Tide
/ height (m)
8:45PM
2.28
9:11AM
1.94
9:44PM
2.31
10:19AM
1.93
10:48PM
2.36
11:28AM
1.98
11:52PM
2.43
12:34PM
2.07
12:55AM
2.51
1:36PM
2.19
1:53AM
2.58
2:32PM
2.32
2:48AM
2.63
Low Tide
/ height (m)
2:16PM
0.51
3:11AM
0.56
3:14PM
0.54
4:16AM
0.51
4:19PM
0.53
5:22AM
0.42
5:27PM
0.49
6:26AM
0.30
6:33PM
0.41
7:25AM
0.18
7:35PM
0.31
8:20AM
0.07
8:33PM
0.24
Sunday
28
Monday
29
Tuesday
30
Wednesday
31
Thursday
01
Friday
02
Saturday
03
Sunrise5:58--5:58--5:58--6:00--6:00--6:00--6:01--
Sunset-5:30--5:30--5:30--5:31--5:32--5:32--5:34-
clear
clear
clear
clear
part cloud
clear
clear
clear
clear
clear
clear
clear
clear
clear
clear
clear
part cloud
clear
part cloud
part cloud
clear
Rain (mm)
---------------------
Temp. °C303025293025303026293026292925293026292726
Feels °C (?)303328303227302924282924282824303228312929
  • Map Icons:
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  • 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 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.

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