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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan <br />Volume 2 — Hazard Inventory <br />�.7,,,;< Hazard Assessment: HEAT, EXTREME <br />4.3.7.1. Definition <br />4.3.7.2. Range of Magnitude <br />The magnitude of extreme heat can vary greatly. You can have extreme heat events where you have <br />shorter periods (3-5 days) with much higher -than -normal temperatures, or you can have longer periods <br />(2-3 weeks) with temperatures only 5-10 degrees higher than normal temperatures. <br />• Hottest Heat Wave on record MN: July 18, 2011 <br />• Longest Heat Wave on record MN: June 3-10, 2021 <br />• Most Recent Heat Wave for Hennepin County: August 251h, 2013 <br />• Deadliest MN Heat Wave: August 4-8, 2001; 5 fatalities <br />4.3.7.3. Spectrum of Consequences B2b <br />Extreme heat can be just as deadly as other natural hazards by pushing the human body beyond its limits. <br />Under normal conditions, the body's internal thermostat produces perspiration that evaporates and cools <br />the body. However, in extreme heat and high humidity, evaporation is slowed, and the body must work <br />extra hard to maintain a normal temperature. Most heat disorders occur because the victim has been <br />overexposed to heat or has over exercised for his or her age and physical condition. Effects can be seen <br />through just a few people or by many depending on extent the temperatures rise above normal, or other <br />hazards occurring simultaneously. People most at risk include elderly and very young persons, chronically <br />ill patients, socially isolated people, urban residents, and people without access to air conditioning. <br />There are different conditions, or disorders, related to extreme heat illnesses: heat stress, heat <br />exhaustion, heat stroke, and hyperthermia. Heat stress is the perceived discomfort and physiological <br />strain associated with exposure to hotter than normal environment, especially during physical activity. <br />Heat exhaustion is a mild -to -moderate illness due to water or salt depletion resulting from exposure to <br />extreme heat conditions or strenuous physical activity. Heat stroke is a severe illness resulting from <br />exposure to environmental heat, or strenuous physical exercise during extreme heat conditions. Heat <br />stroke is characterized by a human body core temperature greater than 1040F along with central nervous <br />system abnormalities such are delirium, convulsions, or coma. Heatstroke can have a fast onset and poor <br />survival rate. <br />131 <br />