Observations on the Last Winter Temperature Occurrence During Spring/Summer in Five Florida Cities, 1948–2021

highlights: • Much of the Southeast, specifically Florida, has not been examined for changes in the timing of the seasonal transition from winter temperatures to spring temperatures. • Tampa and Jacksonville have positive trendlines for linear regression, indicating that winter has increased in length on average, Orlando and Miami have negative trendlines for linear regression, indicating that winter has decreased in length on average. Meanwhile, Pensacola has virtually no change. • Overall, Florida is not consistent in either positive or negative trends but varies by location. Miami is the only location with significant results in both Mann-Kendall tests and linear regression. abstract: It is evident that human activity is now large enough to influence earth’s climate. Many locations experienced progressively less cold weather during the last century, leading to generalizations about season length. However, much of the Southeast, specifically Florida, has not been examined for changes in the timing of the seasonal transition from winter temperatures to spring temperatures. We examined five Florida locations: Jacksonville, Miami, Orlando, Pensacola, and Tampa, representing northeast, southern, central, northwest/panhandle, and west-central respectively. The time series of the latest winter temperature dates are tested for trends using linear regression and the Mann-Kendall rank statistic. Overall, these areas are not consistent in either positive or negative trends but vary by location. While Tampa and Jacksonville have positive trendlines for linear regression, indicating that winter has increased in length on average, Orlando and Miami have negative trendlines for linear regression, indicating that winter has decreased in length on average. Meanwhile, Pensacola has virtually no change. Miami is the only location with significant results in both Mann-Kendall tests and linear regression. This information narrows the knowledge gap on Florida’s winter-to-spring transition since the mid-20th century and may be valuable for both tourism and agricultural interests.