Montevideo sits on the north bank of the Rio de la Plata, and its seasons run opposite to the Northern Hemisphere: December through February is high summer, June through August is winter. The climate is mild and humid year-round, without extreme heat or hard freezes, but wind off the river and the Atlantic shapes daily life as much as temperature does.

The decision usually comes down to whether you want the beach-and-festival energy of summer or the quieter, cheaper, more local city of the shoulder and cold months. Montevideo also hosts the longest Carnival in the world, which puts January and February at the center of the cultural calendar.

Prices and crowds peak sharply from mid-December to late February, when Uruguayans and Argentines flood the coast. The rest of the year the city stays walkable, affordable, and easy, with autumn (March to May) offering the best all-round balance.