In an effort to keep Clark County residents and visitors aware of heat associated illness and mortality, the Southern Nevada Health District provides monthly extreme heat updates. The surveillance begins in April and ends in October. The Centers for Disease Control and Prevention defines extreme heat as summertime temperatures reaching higher than average levels of heat or humidity for a particular location and time of year. Heat-related illness occurs when a person’s body temperature rises faster than it can cool down, which may lead to heat exhaustion or heat stroke, ultimately damaging the brain or other vital organs. Older adults, the very young, and those with mental illness or chronic disease have the highest risk of heat-related illness. However, anyone can be affected if participating in strenuous physical exercise in hotter weather.