Miami has a tropical monsoon climate with warm winters and very hot summers, and a marked drier season in the winter. Although it is relatively cooler than most other tropical places in the winter and does get occasional 40 degree Fahrenheit (4 °C) lows, Miami nevertheless meets the minimum requirements to be in the tropical climate zone, making it one of the northernmost major cities on Earth within this classification.
The city’s sea-level elevation, coastal location, position just above the Tropic of Cancer, and proximity to the Gulf Stream shape its climate. Average winter high temperatures, from December to March, range from 76.4–80.3 °F (24.7–26.8 °C). January is the coolest month with an average daily temperature of 68.2 °F (20.1 °C). Low temperatures fall below 50 °F (10 °C) about 10–15 nights during the winter season, after the passage of cold fronts that produce much of the winter rainfall.
Based on records from Miami International Airport, the National Weather Service defines two meteorological seasons in Miami, summer and winter. Summer is warm and humid, and has frequent showers and thunderstorms. Winter is cooler and drier, with lower rain totals. Spring and autumn are treated as part of winter because they are also cooler and less rainy than summer. Summer in Miami is defined as the period during which the average daily dew point temperature is above 70 °F (21 °C). The rainy season typically begins on the first day that occurs, or within a few days later. Similarly, daily rainfall in Miami decreases sharply when the average daily dew point falls to 70 °F (21 °C) or below, although in some years a stalled front to the south of the Florida peninsula may cause rains to continue for a few more days. During the years 1956 to 1997, the date summer began ranged from April 16 to June 3, with a median date of May 21. During those same years, the date summer ended ranged from September 24 to November 1, with a median date of October 17. During the summer, temperatures range from the mid 80s to low 90s °F (29–35 °C) and are accompanied by high humidity, though the heat is often relieved in the afternoon by thunderstorms or a sea breeze that develops off the Atlantic Ocean. Much of the year’s 61.9 inches (1,572 mm) of rainfall occurs during this period. Dew points in the warm months range from 71.9 °F (22.2 °C) in June to 73.7 °F (23.2 °C) in August.
Extremes range from 27 °F (−2.8 °C) on February 3, 1917 to 100 °F (38 °C) on July 21, 1942. While Miami has never recorded snowfall at any official weather station since records have been kept, snow flurries fell in some parts of the city on January 19, 1977.
Hurricane season officially runs from June 1 through November 30, although hurricanes can develop beyond those dates. The most likely time for Miami to be hit is during the peak of the Cape Verde season, which is mid-August through the end of September. Although tornadoes are uncommon in the area, one struck in 1925 and another in 1997. Around 40% of homes in Miami are built upon floodplains and are considered as flood-risk zones.
Miami falls under the Department of Agriculture’s 10b/11a plant hardiness zone.
Miami is one of the major coastal cities and major cities in the United States that will be most affected by climate change. Global sea level rise, which in Miami will be 31 inches until 2060, will lead to an increase in storm damage, more intense flooding and will threaten the city’s water supply. Real estate prices in Miami already reflect the increase in prices for real estate at a higher elevation within the city compared to real estate at a lower elevation.