Climate of Miami

The climate of Miami is classified as having a tropical monsoon climate with hot and humid summers; short, warm winters; and a marked drier season in the winter. Its sea-level elevation, coastal location, position just above the strong Tropic of Cancer, and proximity to the Gulf Stream shape its climate.

With January averaging 68.6 °F (20.3 °C), winter features warm temperatures; cool air usually settles after the passage of a cold front, which produces much of the little rainfall. Lows sometimes fall to or below 50 °F (10 °C), with an average 3 such occurrences annually, but rarely 40 °F (4 °C); from 1981 to 2010, temperatures reached that level in only eight calendar years. Highs generally reach 70 °F (21 °C) or higher, and fail to do so on only an average of 12 days annually.

The Rainy season officially begins May 15th and continues until October 15th. During this period, highs are in the mid 80s to mid 90s (29–35 °C), accompanied by high humidity, though the heat is often relieved by afternoon thunderstorms or a sea breeze that develops off the Atlantic Ocean, which then allow lower temperatures, but conditions still remain very muggy. Much of the year's 67.41 inches (1,710 mm) of rainfall occurs during this period. Extreme temperatures range from 27 F on February 3, 1917, to 100 °F on July 21, 1942, (−1.8 to 38 °C), the only triple-digit (°F) reading on record; the more recent freezing temperature seen at Miami International Airport was on December 25, 1989. The highest daily minimum temperature is 84 °F (29 °C) on August 4, 1993 and September 7, 1897 (although the corresponding record for Miami Beach is 90 °F or 32 °C on July 17, 2001), and conversely, the lowest daily maximum temperature is 32 °F (0 °C) on February 19, 1899.

While Miami has never officially recorded any accumulating snowfall since records have been kept, there were non-accumulating snow flurries in some parts of the city on January 19, 1977 during the cold wave of January 1977. Weather conditions for the area around Miami were recorded sporadically from 1839 until 1900, with many years-long gaps. A cooperative temperature and rainfall recording site was established in December 1900 in what is now Downtown Miami. An official Weather Bureau Office opened in Miami in June 1911. A record setting 12-day cold snap in January 2010 was the coldest period since at least the 1940s.

Miami receives abundant rainfall, one of the highest among major cities in the United States. Most of this rainfall occurs from mid-May through early October. Miami has an average annual rainfall of 61.9 inches (1,570 mm), whereas nearby Fort Lauderdale and Miami Beach receive 66.7 inches (1,690 mm) and 57.18 inches (1,450 mm), respectively, which demonstrates the high local variability in rainfall rates.

Miami reports more thunderstorms than most US cities, with about eighty days per year having thunder reported. These storms are often strong, with frequent lightning and very heavy rain. Occasionally, they can be severe with damaging straight line winds and large hail. Tornadoes and waterspouts sometimes occur, although violent tornadoes of the type seen in other parts of the United States are rare in Florida.

During El Niño events, Miami becomes cooler than normal during the dry season with above average precipitation. During La Niña, Miami becomes warmer and drier than normal.

While the climate for much of Florida is humid subtropical, much of South Florida qualifies as one of several tropical classifications (Köppen Aw, As, Am, or Af). with the Tropical parts of Southeastern Florida falling into USDA zone 10b to 12a for plant hardiness, where annual extreme low temperatures range from 35 to 55 °F (2 to 13 °C), versus zones 9a-10b in Central Florida, and zones 8b-9b in northern Florida. With global warming, the urban heat island effect, as well as the warm waters provided by the Gulf Stream, the barrier islands and coastal portions of the metroarea including Miami Beach & Miami, made it into hardiness zone 11a by 2012. With most Miami-Dade cities (like Hialeah, Coral Gables, etc) joining in the 2023 USDA update Miami Beach has virtually no freezing weather in its history and few instances of sub-40 °F (4 °C) weather.