Increased risk of heat waves in Florida: Characterizing changes in bivariate heat wave risk using extreme value analysis

• We employ a novel approach to model bivariate heat waves across Florida.
• High maximum combined with high minimum daily temperatures are examined.
• Models have high spatial resolution and changes are explored from 1950 to 2000.
• Frequency, magnitude, duration, and timing of heat wave events are explored.
• Heat waves are becoming increasingly frequent, more intense, and of a longer duration.

Maximum and minimum daily temperatures from the second half of the 20th century are examined using a high resolution dataset of 833 grid cells across the state of Florida. A bivariate Extreme Value Analysis Point Process approach is used to model characteristics including the frequency, magnitude, duration, and timing of periods or heat waves during which both daily maximum and minimum temperatures exceed their respective 90th percentile thresholds. Variability in heat wave characteristics is examined across the state to give an indication of those areas where heat waves with certain characteristics may be more likely to occur. Changes in heat wave characteristics through time are examined by halving the temperature record and determining changes to heat wave characteristics between the two periods. This exploration of changes in heat wave risk through time gives a possible suggestion of trends in future heat wave risk. Findings indicate that there is considerable spatial variability in heat wave characteristics although heat waves have become increasingly frequent and intense throughout much of the state.