Fair Warning Act of 2019 This bill bars an employer from ordering a site closing or mass layoff until 90 calendar days after the employer has served written notice of such an order to (1) each representative of the affected employees as of the time of the notice or each affected employee, (2) the Department of Labor and the governor of the state where the site closing or mass layoff is to occur, and (3) the state or entity designated by the state to carry out rapid response activities. No notice shall be required if the site closing or mass layoff is because of any natural disaster, such as a flood, earthquake, or a drought ravaging the farmlands of the United States. Labor shall maintain a guide of benefits and services that may be available to affected employees, including unemployment compensation, trade adjustment assistance, COBRA continuation coverage, and early access to training services and other services, including counseling services.