The day: from the morning calm to the afternoon wind
At night the air near the ground cools, gets heavy and sits still in the valley, even while it keeps blowing up high. By mid-morning the sun heats the ground, the layers mix and the wind from above comes down. That is why the Laguna de los Tres moraine at 10 am and at 3 pm are two different places, and why we leave early: the last climb is best done before noon. Towards evening, as the sun drops, it usually eases again.
The week: the wind comes in waves
Pacific storms pass every few days, west to east, like carriages on a train. As one approaches, the wind builds for a day or two, hits hard with the front (often with rain or snow up high), and once it passes there are one or two calmer, clearer days with cold southern air. A typical gale lasts 24 to 48 hours up high; the ones that last three or four days in a row are few per season.
That is why a three- or four-day stay almost always holds one good day for Laguna de los Tres. If you come for a single day, it is a lottery.
How to see it coming
- The cloud on Fitz Roy
- A lenticular cloud, like a hat or a plate, sitting still on the summit: strong wind at height, and often a front arriving within 12 to 24 hours.
- The western sky
- High thin clouds coming in off the Ice Field, a halo around the sun: the front’s moisture is already overhead.
- The pressure
- If your watch’s barometer falls fast, the wind rises. Drops of more than 3 hPa in three hours announce a gale.
- The gust forecast
- Not the mean wind in town: the gusts at 1,200 m. It is what we check every morning in our mountain forecast.
The year, month by month
| Month | Daily peak gust, lake | Days over 60 km/h | Calm days (under 40) | Mean wind, town |
|---|---|---|---|---|
| January | 67 km/h | 17 of 30 | 5 of 30 | 15 km/h |
| February | 63 km/h | 17 of 30 | 7 of 30 | 15 km/h |
| March | 63 km/h | 16 of 30 | 7 of 30 | 14 km/h |
| April | 60 km/h | 14 of 30 | 9 of 30 | 13 km/h |
| May | 50 km/h | 10 of 30 | 13 of 30 | 11 km/h |
| June | 53 km/h | 11 of 30 | 11 of 30 | 11 km/h |
| July | 52 km/h | 11 of 30 | 12 of 30 | 12 km/h |
| August | 56 km/h | 13 of 30 | 10 of 30 | 12 km/h |
| September | 58 km/h | 14 of 30 | 11 of 30 | 13 km/h |
| October | 62 km/h | 16 of 30 | 8 of 30 | 15 km/h |
| November | 63 km/h | 17 of 30 | 6 of 30 | 15 km/h |
| December | 64 km/h | 16 of 30 | 6 of 30 | 15 km/h |
Average 2016 to 2025: the strongest gust of each day between 8 am and 8 pm at the height of Laguna de los Tres (1,170 m) and the mean wind in town (400 m). Copernicus ERA5 reanalysis via Open-Meteo.
The calm months are May, July and June; the windiest, January, December and February. Why that is, and what it means for choosing when to come, is in the months article and the summer-and-winter one. Read more →
The live wind map, the wind on the trail right now and the full guide to the Patagonian wind: Read more →
Questions
What time of day is least windy in El Chaltén?
Before dawn and early morning, before the sun mixes the valley air. Late afternoon it usually eases again. The peak is between midday and 5 pm.
How many days does a windstorm last?
Usually one or two strong days up high, with a front in the middle. Then one or two calmer days follow. Three- or four-day gales exist, but there are few per season.
Can you know a week ahead?
For two or three days, fairly well. Beyond that, the European model is run 51 times and if the runs disagree the forecast is uncertain. Our mountain forecast shows that range day by day.
Is the hike cancelled when it is windy?
Almost never: it is changed. We move the outing to the best day of your stay or go to a sheltered valley, like the Río Eléctrico or Laguna Torre.