Avellanas Rivermouth surfForecast / Guanacaste / Costa Rica

information circle16 Day Weather and Surf, issued 5 am Sunday 31 May 2026 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
30.4° C
(Which is 1.8°C warmer than normal for this time of year)

Avellanas Rivermouth surf forecast from 31 May 2026:

  • Best quality surf: Sunday 31 May, 3PM (local time) - 4.5ft (1.3m), 19s period, SW swell with cross-offshore winds.
  • Most powerful swell: Thursday 4 Jun, 9PM (local time) - 5.5ft (1.7m), 19s period, SW swell with 1,967 kJ wave energy.
  • Next surfable swell (1★+): Sunday 31 May, 3PM (local time) - 4.5ft (1.3m), 19s period with SW swell.

Best Forecast Surf Conditions for Avellanas Rivermouth this week:

The surf forecast for Avellanas Rivermouth over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Sunday (May 31) at 3PM. The primary swell is predicted to be 1.3m and 19s period with a secondary swell of 1.2m and 14s. The wind is predicted to be cross-offshore as the swell arrives.

The most powerful waves expected at Avellanas Rivermouth in the next 16 days are 1.7m 19s and forecast to arrive on Thursday (Jun 04) at 9PM. Winds are predicted to be cross-onshore at the time the swell arrives.

Wave TypeTime (CST) & Date Wave Height & Period
Next good surf (1 star+) 3PM (Sun 31st May)4.5ft (1.3m) 19s
Best Surf 3PM (Sun 31st May)4.5ft (1.3m) 19s
Most Powerful 9PM (Thu 4th Jun)5.5ft (1.7m) 19s

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


Updates in  hr  min  s Forecast update imminent

Short Range Forecast

Moderate rain (total 18mm), heaviest on Tue night. Warm (max 31°C on Mon morning, min 27°C on Sun night). Wind will be generally light.

Days 4-6 Weather Summary

Heavy rain (total 99mm), heaviest during Thu night. Warm (max 30°C on Wed morning, min 24°C on Fri night). Wind will be generally light.

Sunday
31
Monday
1
Tuesday
2
Wednesday
3
Thursday
4
Friday
5
Saturday
6
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
4
4
4
3
4
2
2
3
3
3
4
3
4
4
4
4
4
3
4
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)
1
SW
20
1.3
SW
19
1.4
SW
18
1.6
SW
18
1.7
SW
17
1.6
SW
16
1.4
SW
16
1.4
SW
16
1.3
SW
15
1.3
SW
15
1.4
SW
18
1.5
SW
18
1.2
SW
18
1.4
SW
16
1.7
SW
18
1.7
SW
17
1.6
SW
17
1.6
SW
16
1.5
SW
16
1.5
SW
16
1.4
SW
16
Wave Graph
Metric surfscale
Energy kJ
746
1210
1326
1615
1702
1436
989
976
743
695
1227
1351
973
894
1842
1722
1560
1401
1115
1074
871
Wind (km/h)
0
SSE
15
WSW
5
ESE
10
NE
20
WSW
15
ENE
15
ENE
15
SW
10
SE
5
ENE
15
SW
5
SE
5
E
10
SSW
0
ESE
5
E
10
SSW
10
E
5
SW
15
WSW
5
S
glassy
cross-off
glassy
cross-on
off
on
on
cross-off
cross-on
cross-on
cross-off
cross-on
glassy
cross-off
glassy
glassy
cross-off
on
cross-off
off
glassy
High Tide
2:43PM2.30m
3:17AM2.07m
3:22PM2.30m
3:56AM2.08m
4:01PM2.28m
4:36AM2.08m
4:40PM2.25m
5:16AM2.07m
5:19PM2.19m
5:56AM2.05m
5:58PM2.12m
6:37AM2.04m
6:39PM2.04m
Low Tide
9:08PM0.31m
9:12AM0.52m
9:46PM0.30m
9:52AM0.52m
10:25PM0.31m
10:31AM0.55m
11:03PM0.35m
11:11AM0.60m
11:40PM0.40m
11:52AM0.66m
00:18AM0.46m
12:35PM0.71m
00:57AM0.52m
thunderstorm
part cloud
rain showers
part cloud
thunderstorm
clear
part cloud
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
thunderstorm
rain showers
part cloud
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
5:20
5:20
5:20
5:20
5:20
5:20
5:20
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:00
6:00
6:00
6:01
6:01
6:01
6:02
1
2
2
3
10
2
2
6
4
5
52
4
2
22
15
34
Temp °C
30
30
29
31
30
29
31
30
29
30
30
28
30
29
26
28
28
27
25
24
25
35
33
34
33
32
34
33
32
32
34
32
32
33
32
31
32
31
30
29
27
29
Swell 1
Height (m)
Direction
Period (s)
1.3
S
15
1.3
SW
19
1.4
SW
18
1.6
SW
18
1.7
SW
17
1.6
SW
16
1.4
SW
16
1.4
SW
16
1.3
SW
15
1.3
SW
15
1.4
SW
18
1.5
SW
18
1.2
SW
18
1.4
SW
16
1.7
SW
18
1.7
SW
17
1.6
SW
17
1.6
SW
16
1.5
SW
16
1.5
SW
16
1.4
SW
16
Energy kJ
743
1210
1326
1615
1702
1436
989
976
743
695
1227
1351
973
894
1842
1722
1560
1401
1115
1074
871
Swell 2
Height (m)
Direction
Period (s)
1
SW
20
1.2
S
14
1.1
S
14
1
S
13
0.9
S
13
0.8
S
12
0.7
S
12
0.7
S
12
0.6
S
11
0.8
SW
19
0.5
S
10
0.5
S
9
1.1
SW
15
1
SW
19
0.6
SSW
14
0.9
SSW
6
1
SSW
7
1.1
SW
7
1
SW
7
0.9
SW
7
0.4
SSW
12
Energy kJ
746
602
467
340
268
184
137
132
83
446
48
41
566
723
149
57
85
103
88
75
47
Swell 3
Height (m)
Direction
Period (s)
0.8
SW
16
0.8
SW
14
0.8
SW
14
0.3
SW
21
0.3
SW
21
0.6
SW
20
0.6
S
10
0.1
NW
15
0.4
SW
21
0.4
S
8
0.4
SSW
6
0.6
S
6
0.6
SSW
14
0.6
SSW
14
0.5
S
13
0.4
SSW
13
0.4
SSW
12
0.2
SSW
26
Energy kJ
302
248
245
72
71
241
75
8
162
23
14
25
143
149
86
55
46
66
Wind waves
Height (m)
Direction
Period (s)
1.6
SW
7
Energy kJ
230
Nearest Offshore or Glassy
Rating
(10 max)
4
4
4
4
4
4
4
3
3
4
4
4
4
4
4
4
4
4
4
4
4
Distance (km)
0
0
0
1
0
1
1
127
1
1
0
1
0
0
0
0
0
1
0
0
0
Best forecast wave conditions in Guanacaste
Rating
(10 max)
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Best forecast wave conditions in Costa Rica
Rating
(10 max)
4
4
4
4
4
4
4
3
4
4
4
4
4
4
4
4
4
4
4
4
4
Header Global
Rating
(10 max)
6
5
4
5
5
5
4
5
4
5
5
5
6
5
5
9
9
8
9
9
8
  • 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 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 16 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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