Zonda Wind: Hot Downslope Gusts in the Argentine Andes

On the eastern slopes of the Andes in western Argentina, there is a powerful regional wind called the Zonda. Like the Chinook in North America or the Föhn in Europe, it is a warm, dry downslope wind – but with its own local flavour and impacts.

Where Does the Zonda Blow?

The Zonda mainly affects:

• The provinces of San Juan, Mendoza and La Rioja in Argentina
• Foothills and valleys along the eastern Andes

In these areas, steep mountains and deep valleys help channel and intensify the wind.

When Is the Zonda Most Noticeable?

Zonda events can occur in different seasons, but they are often noted:

• In late autumn, winter and spring, when snow is present in the high Andes
• Ahead of or behind weather systems crossing southern South America

How Does the Zonda Form?

The Zonda is a type of foehn (downslope) wind. A typical sequence is:

1. Moist air from the Pacific is forced up the western side of the Andes, where it cools, condenses and drops much of its moisture as precipitation.
2. Once over the crest, the now much drier air descends the eastern slopes.
3. As it sinks toward lower elevations, it warms rapidly by compression and becomes very dry.
4. Reaching the foothills and valleys, it appears as a strong, gusty, hot wind – the Zonda.

What Are the Effects of the Zonda?

During a Zonda event, people may experience:

• Sharp temperature rises, sometimes from cool to very warm in a few hours
• Very dry air, which can irritate skin, eyes and respiratory systems
• Strong gusts that lift dust and sand, reducing visibility

In the mountains, sudden warming can:

• Melt snow quickly, increasing the risk of avalanches
• Contribute to changes in river flow downstream

Zonda in Local Life

For residents of western Argentina, the Zonda is a familiar part of regional climate. It can be both helpful – by temporarily warming winter days – and hazardous, by increasing fire risk, triggering health complaints and disturbing daily activities with its strong, dusty gusts.

It can be both helpful – by temporarily warming winter days – and hazardous, by increasing fire risk, triggering health complaints and disturbing daily activities with its strong, dusty gusts.