South America
Best time to ski in South America: natural snow month by month
When natural snow has been most reliable at the 4 resorts Cirque models in South America, month by month, from eleven winters of weather data.
Every resort Cirque models here
Each cell is one month: the share of days with 30 cm or more of modelled natural snow at mid-mountain over the last 11 winters, from brown (often thin) to deep blue (snow-sure). Blank means almost none.
The short answer
The surest time for natural snow in South America has been September. In that month 3 of the 4 resorts Cirque models here were snow-sure in at least 9 of the last 11 winters, meaning mid-mountain had 30 cm or more of modelled natural snow on at least 90% of days.
Month by month
April: none snow-sure in any winter. Most natural snow at Las Leñas (7% of days).
May: 0 of 4 snow-sure. Surest: Las Leñas (1 of 11), Valle Nevado (1 of 11) and Cerro Catedral (1 of 11).
June: 0 of 4 snow-sure. Surest: Las Leñas (5 of 11), Valle Nevado (4 of 11) and Portillo (2 of 11).
July: 1 of 4 snow-sure. Surest: Las Leñas (9 of 11), Valle Nevado (8 of 11) and Portillo (7 of 11).
August: 2 of 4 snow-sure. Surest: Las Leñas (10 of 11), Cerro Catedral (10 of 11) and Valle Nevado (7 of 11).
September: 3 of 4 snow-sure. Surest: Las Leñas (11 of 11), Cerro Catedral (10 of 11) and Valle Nevado (9 of 11).
October: 2 of 4 snow-sure. Surest: Las Leñas (11 of 11), Cerro Catedral (9 of 11) and Valle Nevado (7 of 11).
November: 0 of 4 snow-sure. Surest: Las Leñas (5 of 11), Valle Nevado (3 of 11) and Cerro Catedral (1 of 11).
December: 0 of 4 snow-sure. Surest: Las Leñas (1 of 11) and Valle Nevado (1 of 11).
Resort by resort
Cerro Catedral, Argentina, 1,030–2,100 m: snow-sure August to October.
Las Leñas, Argentina, 2,240–3,430 m: snow-sure July to October.
Portillo, Chile, 2,580–3,310 m: no month snow-sure in 9 of 11 winters. Best: July, usually good (7 of 11).
Valle Nevado, Chile, 2,860–3,670 m: snow-sure September.
Questions
When is the best time to ski in South America?
For natural snow, September. That is when the most resorts Cirque models in South America have been snow-sure over the last 11 winters.
When does natural snow become reliable in South America?
The first month in which any resort Cirque models here was snow-sure in at least 9 of 11 winters is July. Resorts open on their own dates and many use snowmaking earlier.
Which resort in South America has the most reliable snow?
Of those Cirque models, Las Leñas: mid-mountain was snow-sure in 4 months of the year.
Does this include snowmaking?
No. These are modelled natural snow figures only, from ERA5 weather. Groomed pistes with snowmaking often ski better than this.