Surf Forecasts:
Avellanas Rivermouth surf forecast from 19 Jul 2026:
- Best quality surf: Sunday 26 Jul, 12AM (local time) - 4.5ft (1.3m), 19s period, SW swell with glassy winds.
- Most powerful swell: Saturday 25 Jul, 9PM (local time) - 4.5ft (1.3m), 19s period, SW swell with 1,210 kJ wave energy.
- Next surfable swell (1★+): Tuesday 21 Jul, 3PM (local time) - 2.5ft (0.8m), 14s 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 Tuesday (Jul 21) at 3PM. The primary swell is predicted to be 0.8m and 14s period with a secondary swell of 0.7m and 6s. Another secondary swell of 0.7m and 5s is also forecast. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Avellanas Rivermouth in the next 16 days are 1.3m 19s and forecast to arrive on Saturday (Jul 25) at 9PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.7m 5s period and expected on Tuesday (Jul 21) at 12PM.
| Wave Type | Time (CST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Tue 21st Jul) | 2.5ft (0.8m) 14s |
| Best Surf | 12AM (Sun 26th Jul) | 4.5ft (1.3m) 19s |
| Most Powerful | 9PM (Sat 25th Jul) | 4.5ft (1.3m) 19s |
Table - best surf conditions forecast for Avellanas Rivermouth over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s have a look at what’s coming our way. We’ve got a 16-day window, and it’s a bit of a slow starter, but there’s a real treat waiting for the patient ones.
The first few days look pretty average. Sunday the 19th through to Thursday the 24th are mostly a write-off with messy, choppy conditions and weak, inconsistent energy. The swell is small, mostly around 2ft to 3ft, and the wind is all over the place, mostly cross-onshore. There’s a glimmer on Tuesday afternoon, the 21st, when it goes glassy with a 3ft swell from the SW, but it’s small and the energy is weak (463). The real drama starts to build later in the week.
The standout window is from Monday the 27th of July right through to Wednesday the 29th of July. This is where the magic happens. We’ve got a solid groundswell building, and the wind toys with offshore and glassy conditions. The energy climbs significantly, with combined energy values hitting 1567 and 1969 – that’s strong wave energy, plenty of punch. The swell hangs around 4ft to 6ft from the SW, with a long period (16 to 19 seconds). This is proper groundswell, so it’s going to be clean, powerful, and lined up. At Avellanas Rivermouth, the afternoon of the 27th shows clean, cross-offshore wind with a 4ft SW swell and 19-second period – that’s going to be a ripper session. Tuesday the 28th and Wednesday the 29th are the peak, with clean, glassy conditions and 5ft to 6ft SW swell. That’s a bit too big for beginners, but for anyone with a bit of experience, it’s going to be firing. The long period means it’ll be a bit more lined up and better for the rivermouth setup, with longer waits between sets but cleaner, more powerful waves.
After that, from the 30th of July onward, the wind turns nasty again, and the swell drops off, so it’s back to choppy, poor conditions. The final day on the 3rd of August has a bit of clean cross-offshore wind with a 4ft SW swell, but the energy is lower (687), so it’s more of a salvage session than a standout.
So, to put it simply: the first week is a write-off. The best of the best is Monday 27th July through Wednesday 29th July at Avellanas Rivermouth. That’s the window. It’s a bit of a wait, but it’ll be worth it.
Rusty.
Short Range ForecastModerate rain (total 15mm), heaviest on Tue afternoon. Warm (max 31°C on Sun afternoon, min 24°C on Mon night). Winds decreasing (fresh winds from the ENE on Sat night, calm by Tue afternoon). | Days 5-7 Weather SummaryHeavy rain (total 29mm), heaviest during Wed night. Warm (max 29°C on Fri morning, min 23°C on Wed night). Wind will be generally light. | ||||||||||||||||||
Sunday 19 | Monday 20 | Tuesday 21 | Wednesday 22 | Thursday 23 | Friday 24 | ||||||||||||||
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) | SSW 13 | S 13 | S 12 | S 12 | SW 16 | SW 16 | SW 15 | SW 15 | SW 14 | SW 13 | SW 13 | SW 13 | SW 12 | SW 12 | S 7 | SW 18 | SW 24 | SW 9 | SW 21 |
Wave Graph  | |||||||||||||||||||
 kJ | 286 | 276 | 239 | 247 | 366 | 361 | 370 | 301 | 293 | 250 | 173 | 161 | 92 | 93 | 66 | 93 | 661 | 271 | 1015 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross-on | cross | cross-on | cross-on | cross-on | cross-on | on | glassy | on | cross-on | off | cross-on | cross-on | on | cross-on | cross-on | cross | cross-on |
High Tide | 6:15AM2.54m | 6:31PM2.31m | 7:02AM2.45m | 7:20PM2.15m | 7:48AM2.33m | 8:10PM2.00m | 8:37AM2.20m | 9:04PM1.86m | 9:29AM2.09m | 10:03PM1.77m | 10:25AM2.02m | 11:07PM1.72m | |||||||
Low Tide | 11:56PM0.10m | 12:28PM0.30m | 00:41AM0.24m | 1:19PM0.40m | 1:27AM0.40m | 2:10PM0.51m | 2:15AM0.55m | 3:04PM0.60m | 3:06AM0.68m | 4:02PM0.67m | 4:03AM0.76m | 5:03PM0.69m | |||||||
 |  |  | | |  |  | |  |  |  | |  | | | | | | | |
 | — | 5:30 | — | — | 5:30 | — | — | 5:30 | — | — | 5:30 | — | — | 5:31 | — | — | 5:31 | — | — |
 | — | — | 6:08 | — | — | 6:07 | — | — | 6:07 | — | — | 6:07 | — | — | 6:07 | — | — | 6:07 | — |
mm | — | — | — | — | — | 2 | 3 | 3 | 7 | 2 | 1 | 6 | 14 | — | — | — | — | 6 | 3 |
Temp °C | 28 | 30 | 31 | 27 | 30 | 27 | 25 | 30 | 27 | 25 | 27 | 27 | 24 | 28 | 28 | 27 | 29 | 29 | 25 |
Feels °C | 27 | 31 | 33 | 26 | 29 | 29 | 27 | 33 | 32 | 29 | 29 | 31 | 28 | 28 | 27 | 26 | 30 | 32 | 29 |
Swell 1 Height (m) Direction Period (s) | SSW 13 | S 13 | S 12 | S 12 | SW 16 | SW 16 | SW 15 | SSW 12 | SW 14 | SW 13 | S 7 | SSW 7 | SSW 7 | SSW 7 | S 7 | SW 8 | SW 9 | SW 9 | SW 8 |
| kJ | 286 | 276 | 239 | 247 | 366 | 361 | 370 | 228 | 293 | 250 | 66 | 84 | 89 | 72 | 66 | 93 | 249 | 268 | 250 |
Swell 2 Height (m) Direction Period (s) | S 6 | S 7 | SSW 6 | SSW 6 | S 13 | S 12 | S 12 | SW 15 | SSW 6 | S 7 | SW 13 | SW 13 | SW 12 | SW 12 | SW 8 | S 7 | SW 24 | SW 24 | SW 21 |
| kJ | 31 | 43 | 43 | 43 | 212 | 146 | 144 | 301 | 44 | 48 | 173 | 161 | 92 | 93 | 40 | 47 | 661 | 271 | 1015 |
Swell 3 Height (m) Direction Period (s) | SW 19 | SW 19 | SW 18 | SW 18 | S 7 | SSW 7 | SSW 7 | W 11 | S 12 | S 12 | S 11 | SSW 11 | SSW 11 | S 10 | N 5 | SW 18 | SW 13 | N 5 | SW 16 |
| kJ | 96 | 217 | 194 | 192 | 34 | 36 | 49 | 10 | 101 | 99 | 63 | 40 | 39 | 19 | 11 | 79 | 57 | 11 | 90 |
Wind waves Height (m) Direction Period (s) | NE 4 | NNE 3 | N 3 | NNE 4 | NNE 5 | — | — | NNE 3 | N 5 | NNE 3 | NE 3 | — | N 5 | NNE 5 | — | NE 3 | N 4 | — | — |
| kJ | 32 | 2 | 5 | 37 | 39 | — | — | 9 | 25 | 7 | 3 | — | 23 | 14 | — | 2 | 13 | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 1 | 7 | 1 | 19 | 7 | 7 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 7 | 1 | 1 | 1 | 7 | 1 |
Best forecast wave conditions in Guanacaste | |||||||||||||||||||
Best forecast wave conditions in Costa Rica | |||||||||||||||||||
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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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