Temperatures in Florida have risen more than 2°F since the beginning of the 20th century. Under a higher emissions pathway, historically unprecedented warming is projected during this century. Increases in the rate of soil moisture loss due to rising temperatures will likely increase the intensity of naturally occurring droughts.
The number of landfalling hurricanes in Florida is highly variable from year to year. Hurricane rainfall rates are projected to increase as the climate continues to warm.
Global sea level is projected to rise, with a likely range of 1–4 feet by 2100, and will likely increase the frequency of nuisance-level coastal flooding and contribute to saltwater contamination of coastal groundwater reservoirs.
Due to its location at subtropical latitudes and adjacent to the warm waters of the Gulf of Mexico and western Atlantic, Florida has a climate characterized by hot, humid summers and mild winters. The Bermuda High, a semipermanent high-pressure system off the Atlantic coast, plays an important role in the climate of the state, particularly in the summer. Typically, the Bermuda High draws moisture northward or westward from the Atlantic Ocean, causing warm and moist summers with frequent thunderstorms in the afternoons and evenings. Average (1991–2020 normals) temperatures in January range from the lower 50s (°F) in the northern portion of the state to the upper 60s (°F) in the south. During July, typically the hottest month of the year, average temperatures in the low 80s (°F) are prevalent throughout the state. Statewide annual average (1895–2020) precipitation is 53.7 inches, with more precipitation falling during the warmer months of June through September.
Temperatures in Florida have risen more than 2°F since the beginning of the 20th century (Figure 1). Although there has been a general lack of daytime warming (Figure 2a), nighttime warmth has increased dramatically since 1995 (Figure 3); the number of very warm nights during the 2015 to 2020 period was more than double the numbers of the mid-20th century (1930–1944). While Florida typically experiences far fewer days with temperatures exceeding 100°F than most other southern states, it is the most humid state in the Nation. Extended periods of extreme heat, especially when combined with high humidity, can result in heat-related illness among vulnerable populations and place excess stress on agricultural production, water supplies, and energy generation.
During the cold season, extratropical cyclones and associated fronts are responsible for significant day-to-day variability in the weather. While the temperatures associated with cold waves are warmer than in areas to the north, they can have major impacts on those sectors adapted to the generally mild climate, such as agriculture. For example, several strong freezes since the beginning of the 19th century have gradually forced the citrus and other industries (e.g., winter vegetables and sugarcane) to migrate from North Florida into South Florida. The annual average (1991–2020) number of freezing nights varies from greater than 20 in the far northern part of the state to 0 in the south (Figure 4). Throughout 80 years of record keeping, Miami International Airport has dropped below freezing only 7 times and not once since 1989. Subfreezing air sometimes reaches as far south as Central Florida, causing major damage to citrus crops. A severe cold outbreak lasting more than a week in January 2010 resulted in more than $200 million in losses to the Florida citrus industry. There is no long-term trend in the number of freezing nights, but there has been a decrease from the high numbers of the late 1970s (Figure 2b).
Total annual precipitation varies widely from year to year (Figure 2c). The driest year on record was 2000, with 40.3 inches of precipitation, and the wettest was 1947, with 72.9 inches. The driest consecutive 5-year interval was 2006–2010, with an average of 47.9 inches per year, and the wettest was 1945–1949, with an average of 60.2 inches per year. Historically, the number of 4-inch extreme precipitation events has been highly variable but has been near or above average since 1995 (Figure 5). Two notable extreme precipitation events occurred in 2014. During January 9–10, torrential rain fell in the West Palm Beach area, with more than 10 inches at Fort Pierce and more than 14 inches at Sun Valley. On April 29 in the Panhandle, more than 15 inches fell in Pensacola and about 20 inches in Milton. Drought is a persistent climate threat for Florida, resulting in water supply reductions, disruptions to agriculture, and increased risk of wildfires. In every decade since 1900, the state has been impacted by at least one severe and widespread drought.
Thunderstorms are ubiquitous during the summer. Florida experiences the highest annual number of thunderstorms in the United States. Hurricanes and intense coastal storms are the most serious weather threats. Hurricane strikes occur frequently along the Florida coast, with hurricane-force winds impacting the state an average of 3 times every 5 years (Figure 2d). In 2018, Hurricane Michael (Category 5) struck the Panhandle, nearly destroying Mexico Beach and causing extensive damage to Panama City and Tyndall Air Force Base and more than $20 billion in damages. Michael was the strongest hurricane on record to make landfall along the Florida Panhandle. In 2017, Hurricane Irma (Category 4) made landfall at Cudjoe Key, then crossed over the Gulf of Mexico and made landfall again in the Florida Panhandle. The Florida Keys were heavily impacted, and near-historic levels of storm surge caused significant coastal flooding in Jacksonville.
Under a higher emissions pathway, historically unprecedented warming is projected during this century (Figure 1). Even under a lower emissions pathway, annual average temperatures are projected to most likely exceed historical record levels by the middle of the century. However, a large range of temperature increases is projected under both pathways, and under the lower pathway, a few projections are only slightly warmer than historical records. By 2050, most of the state is projected to see an increase of more than 50 days with temperatures of 95°F or higher. The summer heat index is projected to increase by 8° to 15°F, the largest escalation in the Nation.
Increases in the frequency and intensity of extreme precipitation and drought are projected. Projected changes in summer precipitation are uncertain (Figure 6); however, even if precipitation remains constant, higher temperatures will increase the rate of soil moisture loss and likely lead to more intense droughts. Decreased water availability, exacerbated by population growth and land-use change, will continue to increase competition for water and affect the region’s economy and unique ecosystems. Increasing drought intensity will likely trigger more frequent wildfire events. Typically, the state exhibits a peak in wildfire activity from January to mid-June, a period when tropical moisture is reduced and occasional cold fronts usher in dry, windy conditions. In 2020, Florida experienced 2,381 wildfires, ranking fifth in the Nation for number of wildfires; a total of 99,413 acres burned. While the annual frequency of hurricanes has remained relatively stable throughout the 20th and early 21st centuries (Figure 2d), hurricane rainfall is expected to increase for Florida as the climate continues to warm.
Since 1900, global average sea level has risen by about 7–8 inches. It is projected to rise another 1–8 feet, with a likely range of 1–4 feet, by 2100 as a result of both past and future emissions from human activities (Figure 7). Sea level rise has caused an increase in tidal floods associated with nuisance-level impacts. Nuisance floods are events in which water levels exceed the local threshold (set by NOAA’s National Weather Service) for minor impacts. These events can damage infrastructure, cause road closures, and overwhelm storm drains. Tidal flood days (all days exceeding the nuisance-level threshold) remain rare at Key West, but as global sea level rises, they are projected to become a common occurrence (Figure 8). Increased inland flooding during heavy precipitation events in low-lying coastal areas is a threat, because mere inches of sea level rise have the potential to impair the capacity of stormwater drainage systems to empty into the ocean. Sea level rise presents major challenges to South Florida’s existing coastal water management system due to a combination of increasingly urbanized areas, aging flood control facilities, flat topography, and permeable limestone aquifers. Increases in nuisance-level coastal flooding and saltwater contamination of coastal groundwater reservoirs are likely consequences of sea level rise.