Preventing Health Emergencies And Temperature-related Illness and Deaths Act of 2020 or the Preventing HEAT Illness and Deaths Act of 2020 This bill establishes the National Integrated Heat Health Information System Interagency Committee, which shall focus on reducing the health risks of extreme heat over multiple time scales. The committee must, among other activities (1) develop a strategic plan to coordinate a federal approach to reducing health risks of heat; (2) study health-affected communities, including data collection, warning communications, resiliency, and response capacity; and (3) administer matching grants to increase awareness of heat risks and for projects, such as urban forestry, to reduce the health impacts of extreme heat events. To support the committee's activities, the National Oceanic and Atmospheric Administration shall provide administrative and technical assistance.