Exertional heat stroke (EHS) is a leading cause of sudden death in high school football players. Preparedness strategies can mitigate EHS incidence and severity.To examine EHS preparedness among high school football programs and its association with regional and state preseason heat-acclimatization mandates.Cross-sectional study.Preseason high school football programs, 2017.A total of 910 athletic trainers (ATs) working with high school football (12.7% completion rate).We acquired data on high school football programs' EHS preparedness strategies in the 2017 preseason via an online questionnaire, looking at (1) whether schools' state high school athletic associations mandated preseason heat-acclimatization guidelines and (2) heat safety region based on warm-season wet-bulb globe temperature, ranging from the milder region 1 to the hotter region 3. Six EHS-preparedness strategies were assessed: EHS recognition and treatment education; policy for initiating emergency medical services response; emergency response plan enactment; immersion tub filled with ice water before practice; wet-bulb globe temperature monitoring; and hydration access. Multivariable binomial regression models estimated the prevalence of reporting all 6 strategies.Overall, 27.5% of ATs described their schools as using all 6 EHS-preparedness strategies. The highest prevalence was in region 3 schools with state mandates (52.9%). The combination of a higher heat safety region and the presence of a state mandate was associated with a higher prevalence of reporting all 6 strategies ( = .05). Controlling for AT and high school characteristics, the use of all 6 strategies was higher in region 3 schools with state mandates compared with region 1 schools without state mandates (52.9% versus 17.8%; prevalence ratio = 2.68; 95% confidence interval = 1.81, 3.95).Our findings suggest a greater use of EHS-preparedness strategies in environmentally warmer regions with state-level mandates for preseason heat acclimatization. Future researchers should identify factors influencing EHS preparedness, particularly in regions 1 and 2 and in states without mandates.