Asuncion Valdivia Heat Illness and Fatality Prevention Act of 2020 This bill requires the Department of Labor to promulgate an occupational safety or health standard on prevention of exposure to excessive heat. Excessive heat includes outdoor or indoor exposure to heat at levels that exceed the capacities of the body to maintain normal body functions and may cause heat-related injury, illness, or fatality. In addition, the bill establishes requirements concerning (1) training and education to prevent and respond to heat illness, and (2) whistle-blower protections.