Surf Forecasts:
Las Avellanas surf forecast from 12 Sep 2026:
- Best quality surf: Tuesday 15 Sep, 12AM (local time) - 3ft (0.9m), 18s period, SW swell with offshore winds.
- Most powerful swell: Wednesday 16 Sep, 12PM (local time) - 3.5ft (1.1m), 16s period, SW swell with 644 kJ wave energy.
- Next surfable swell (1★+): Friday 11 Sep, 9PM (local time) - 3.5ft (1.1m), 14s period with SW swell.
Best Forecast Surf Conditions for Las Avellanas this week:
The surf forecast for Las Avellanas over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Friday (Sep 11) at 9PM. The primary swell is predicted to be 1.1m and 14s period. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Las Avellanas in the next 16 days are 1.1m 16s and forecast to arrive on Wednesday (Sep 16) at 12PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.0m 8s period and expected on Monday (Sep 14) at 9PM.
| Wave Type | Time (CST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Fri 11th Sep) | 3.5ft (1.1m) 14s |
| Best Surf | 12AM (Tue 15th Sep) | 3ft (0.9m) 18s |
| Most Powerful | 12PM (Wed 16th Sep) | 3.5ft (1.1m) 16s |
Table - best surf conditions forecast for Las Avellanas over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s break down what’s coming our way for Las Avellanas over the next couple of weeks.
First thing you gotta know: the water is sitting at a warm 87°, which is about 4° warmer than normal for this time of year. That’s a big deal—it’s much warmer than usual, so you can leave the thick rubber at home.
The week starts off a bit slow, but there are a few windows. Friday morning (September 11th) sees some chest-high 4ft swell from the SW, with a solid 16-second period, carrying moderate combined swell energy (725). The wind is a cross-off from the NE at 12 mph, keeping things clean. It’s just a marginal call, though, so don’t get your hopes too high. By Saturday and Sunday, the swell drops off to knee-high, and honestly, it’s not worth paddling out.
Things start looking up Monday morning (September 14th). The swell is only 2ft, but the period jumps to 19 seconds, giving it that long-period, groundswell feel. Energy is light (292), but with a gentle cross-off breeze and clean conditions, a longboard would be your best friend here. The trend continues into Tuesday and Wednesday morning (September 16th), which is a real standout. Wednesday morning shows 4ft of SW swell, 16-second period, and strong moderate energy (741), with offshore ENE winds at 9 mph. The conditions are clean, and that’s about as good as it gets for this stretch. This is your pick of the first week—early Wednesday morning.
The next few days stay small but glassy. Friday morning (September 18th) and Saturday morning (September 19th) both show 2ft to 3ft swell with glassy conditions (zero wind Friday, light SW Saturday). The period is long, 19-20 seconds, which is great for this reef break, as the long lines will wrap in nicely. With glassy conditions, you’ll have a fun, mellow session on the longboard.
Now, looking ahead to the second week, you get a bit more promise. Tuesday morning (September 22nd) has a solid pulse of groundswell, 12ft from the SSW, but with a short 9-second period. The combined energy is sky-high at 2296. That’s a lot of water moving, but it’s going to be raw and powerful—strictly for experts on the largest days, and even then, the short period will make it wall up quickly. It’s a wake-up call, not a casual surf.
Wednesday morning (September 23rd) drops to a more manageable 7ft from the SW, with 8-second period and a moderate energy reading of 817. With a light cross-off breeze and clean conditions, it could still be heavy and punchy for experienced surfers.
Friday (September 25th) and Saturday (September 26th) mornings see the swell back down to waist-to-chest high (2-3ft), with glassy or light offshore winds. The period is moderate (12-13 seconds), making for clean, user-friendly waves for the weekend crew.
At the end of the day, for Las Avellanas, your two standout windows are: the clean offshore conditions on Wednesday morning (September 16th) for the best quality, and the glassy, long-period Saturday morning (September 19th) for the most serene session. Everything else is background noise.
Stay stoked,
Rusty.
Short Range ForecastLight rain (total 3mm), mostly falling on Sat night. Warm (max 32°C on Fri afternoon, min 25°C on Sun night). Wind will be generally light. | Days 5-7 Weather SummaryModerate rain (total 10mm), heaviest on Wed afternoon. Warm (max 31°C on Wed morning, min 25°C on Mon night). Wind will be generally light. | |||||||||||||||||||
Fri 11 | Saturday 12 | Sunday 13 | Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | ||||||||||||||
PM | 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) | SW 15 | SW 14 | SW 14 | SW 14 | SW 13 | SW 13 | SW 13 | SW 19 | SW 19 | SW 18 | SW 18 | SW 15 | SW 17 | SW 16 | SW 16 | SW 16 | SW 15 | SW 14 | SW 14 | SW 14 |
Wave Graph  | ||||||||||||||||||||
 kJ | 623 | 459 | 346 | 341 | 215 | 140 | 138 | 299 | 219 | 246 | 460 | 262 | 587 | 508 | 502 | 620 | 418 | 407 | 401 | 276 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | off | cross-off | cross-on | off | cross-off | cross-off | off | cross-off | cross-on | off | cross-off | cross-on | off | cross-off | cross | off | off | cross-on | cross-off |
High Tide | 3:07AM2.61m | 3:27PM2.48m | 3:48AM2.64m | 4:09PM2.44m | 4:27AM2.60m | 4:49PM2.37m | 5:06AM2.52m | 5:29PM2.26m | 5:44AM2.39m | 6:09PM2.12m | 6:24AM2.24m | 6:51PM1.97m | ||||||||
Low Tide | 8:53PM0.12m | 9:21AM0.12m | 9:34PM0.11m | 10:03AM0.10m | 10:14PM0.15m | 10:44AM0.14m | 10:53PM0.23m | 11:23AM0.22m | 11:31PM0.34m | 12:03PM0.33m | 00:10AM0.47m | 12:45PM0.47m | 00:52AM0.61m | |||||||
 |  | | |  | |  |  |  | | | | | | | | | | | | |
 | — | — | 5:33 | — | — | 5:33 | — | — | 5:33 | — | — | 5:33 | — | — | 5:33 | — | — | 5:31 | — | — |
 | 5:45 | — | — | 5:45 | — | — | 5:45 | — | — | 5:44 | — | — | 5:44 | — | — | 5:43 | — | — | 5:42 | — |
mm | — | — | — | — | 1 | — | 2 | — | — | 1 | — | 1 | 1 | — | — | 3 | 4 | — | 3 | 13 |
Temp °C | 32 | 28 | 32 | 29 | 28 | 32 | 32 | 27 | 31 | 28 | 27 | 30 | 28 | 28 | 31 | 28 | 27 | 31 | 29 | 26 |
Feels °C | 35 | 32 | 35 | 31 | 31 | 33 | 34 | 28 | 34 | 31 | 30 | 33 | 31 | 31 | 33 | 30 | 30 | 34 | 31 | 29 |
Swell 1 Height (m) Direction Period (s) | SW 15 | SW 14 | SW 14 | SW 14 | SW 13 | S 9 | S 9 | S 8 | S 8 | S 8 | S 8 | S 8 | SW 17 | SW 16 | SW 16 | SW 16 | SW 15 | SW 14 | SW 14 | SW 14 |
| kJ | 623 | 459 | 346 | 341 | 215 | 76 | 99 | 92 | 89 | 111 | 130 | 127 | 587 | 508 | 502 | 620 | 418 | 407 | 401 | 276 |
Swell 2 Height (m) Direction Period (s) | S 7 | S 7 | S 8 | S 8 | S 8 | SW 13 | SW 13 | SW 13 | SW 19 | SW 18 | SW 18 | SW 15 | S 8 | S 9 | S 9 | S 8 | S 8 | S 10 | S 9 | S 8 |
| kJ | 47 | 51 | 58 | 49 | 44 | 140 | 138 | 134 | 219 | 246 | 460 | 262 | 111 | 125 | 96 | 69 | 50 | 90 | 76 | 69 |
Swell 3 Height (m) Direction Period (s) | N 4 | WNW 10 | WNW 10 | SW 18 | NNE 4 | SW 18 | N 4 | SW 19 | SW 12 | SW 12 | SW 12 | SW 18 | SW 13 | SW 12 | SW 13 | N 4 | SW 23 | SW 22 | SW 22 | SW 21 |
| kJ | 9 | 19 | 9 | 80 | 3 | 51 | 6 | 299 | 73 | 72 | 49 | 252 | 109 | 95 | 166 | 6 | 86 | 123 | 163 | 220 |
Wind waves Height (m) Direction Period (s) | — | NNE 4 | NNE 4 | — | — | NNE 4 | — | NNE 5 | NE 3 | — | — | — | — | — | N 4 | — | NNW 12 | NNE 4 | — | — |
| kJ | — | 3 | 4 | — | — | 6 | — | 13 | 3 | — | — | — | — | — | 9 | — | 26 | 10 | — | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 19 | 19 | 0 | 19 | 64 | 0 | 20 | 11 | 0 | 0 | 1 | 0 | 7 | 1 | 0 | 0 | 1 | 0 | 0 | 1 |
Best forecast wave conditions in Guanacaste | ||||||||||||||||||||
Best forecast wave conditions in Costa Rica | ||||||||||||||||||||
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Information about the Las Avellanas Surf forecast
The above surf forecast table for Las Avellanas provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Las Avellanas can be found by selecting the local surf guide option on the grey menu. Our Las Avellanas 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 (Las Avellanas) 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 Las Avellanas 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.
Las Avellanas is 45 km (28 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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