According to the Köppen climate classification, Orlando has a humid subtropical climate (Cfa) like much of the deep Southern United States. The two basic seasons in Orlando are a hot and rainy season, lasting from May until late October (roughly coinciding with the Atlantic hurricane season), and a warm and dry season from November through April. The area’s warm and humid climate is caused primarily by its low elevation, its position relatively close to the Tropic of Cancer, and its location in the center of a peninsula. Many characteristics of its climate are a result of its proximity to the Gulf Stream, which flows around the peninsula of Florida.
During the height of Orlando’s humid summer season, high temperatures are typically in the low 90s °F (32–34 °C), while low temperatures rarely fall below the low 70s °F (22–24 °C). The average window for 90 °F (32 °C) temperatures is April 9 to October 14. The area’s humidity acts as a buffer, usually preventing actual temperatures from exceeding 100 °F (38 °C), but also pushing the heat index to over 110 °F (43 °C). The city’s highest recorded temperature is 103 °F (39 °C), set on September 8, 1921. During these months, strong afternoon thunderstorms occur almost daily. These storms are caused by air masses from the Gulf of Mexico and the Atlantic Ocean colliding over Central Florida. They are highlighted by spectacular lightning and can also bring heavy rain (sometimes several inches per hour) and powerful winds as well as rare damaging hail.
During the winter, humidity is much lower and temperatures are more moderate, and can fluctuate more readily. The monthly daily average temperature in January is 60.6 °F (15.9 °C). Temperatures dip below the freezing mark on an average of only 1.6 nights per year and the lowest recorded temperature is 18 °F (−8 °C), set on December 28, 1894. Because the winter season is dry and freezing temperatures usually occur only after cold fronts (and their accompanying precipitation) have passed, snow is exceptionally rare. The only accumulation ever to occur in the city proper since record keeping began was in 1948, although some accumulation occurred in surrounding areas in a snow event in January 1977 that reached Miami. Flurries have also been observed in 1989, 2006, and 2010.
The average annual rainfall in Orlando is 51.45 inches (1,307 mm), a majority of which occurs in the period from June to September. October through May are Orlando’s dry season. During this period (especially in its later months), often a wildfire hazard exists. During some years, fires have been severe. In 1998, a strong El Niño caused an unusually wet January and February, followed by drought throughout the spring and early summer, causing a record wildfire season that created numerous air-quality alerts in Orlando and severely affected normal daily life, including the postponement of that year’s Pepsi 400 NASCAR race in nearby Daytona Beach.
Orlando is a major population center and has a considerable hurricane risk, although it is not as high as in South Florida’s urban corridor or other coastal regions. Since the city is located 42 miles (68 km) inland from the Atlantic and 77 miles (124 km) inland from the Gulf of Mexico, hurricanes usually weaken before arriving. Storm surges are not a concern since the region is 100 feet (30 m) above mean sea level. Despite its location, the city does see strong hurricanes. During the notorious 2004 hurricane season, Orlando was hit by three hurricanes that caused significant damage, with Hurricane Charley the worst of these. The city also experienced widespread damage during Hurricane Donna in 1960.
Tornadoes are not usually connected with the strong thunderstorms of the humid summer. They are more common during the infrequent cold days of winter, as well as in passing hurricanes. The two worst major outbreaks in the area’s history, a 1998 outbreak that killed 42 people and a 2007 outbreak that killed 21, both happened in February.