According to the Worker Adjustment and Retraining Notification $($WARN$)$ Act,

all but small employers and public employers are required to provide written notice of a plant closing or mass layoff no less than $60$ days in advance.

employers who have less than $500$ full$-$time employees are not covered under the act.

employers are not required to give an advance notice in case of mass layoffs.

all actions arising out of a natural disaster such as a flood, earthquake, or drought require an employer to provide $60$ days' advance notice to the employees