Curitiba has a Maritime Temperate climate or Subtropical highland climate (Cfb), according to the Köppen classification. Located in Southern Brazil, the humid city lies in a temperate zone.

Current weather at Curitiba's Afonso Pena International Airport
 

Curitiba is located in a plateau and the flat terrain with flooded areas contribute to its mild and damp winter, with average temperature of 13 °C (55 °F) in the coldest month, sometimes falling below 0 °C (32 °F) on the coldest days. During summertime, the average temperature is around 21 °C (70 °F), but it can get above 32 °C (90 °F) on hot days. Snowfall was experienced in 1928,1942, 1955, 1962, 1975 and 1988. Among Brazil's twenty-six state capitals, Curitiba is the coldest due its altitude, despite being 600 kilometres (370 mi) north of Porto Alegre, which is the southernmost state capital in Brazil, but located at sea level. Heat waves during winter and cold waves during summer are not uncommon, and even within a single day there can be great variation, a typical feature of subtropical climates. Several factors contribute to the climate's variable nature: The flat terrain surrounded by mountains in a rough circle with radius 40 kilometres (25 mi) helps block the winds, allowing the morning mist to cover the city on cold mornings.

The flatness of the terrain hinders quick water drainage after rain, therefore providing a good source of water vapor for the atmosphere. Cold fronts come often from Antarctica and Argentina all year round, bringing tropical storms in summer and cold winds in winter. They can move very quickly, with no more than one day between the start of the southern winds and the start of rain. Curitiba's weather is also influenced by the dry air masses that dominate Brazil's midwest most of the year, bringing cold and dry weather, sometimes even in winter.

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