California law does not require notice for layoff of employees who were hired with the understanding that their employment is seasonal and temporary.
Also excluded are employees who were hired for a particular project or undertaking by an employer subject to Wage Orders 11, 12 or 16 covering the broadcasting, motion picture, construction, drilling, logging and mining industries, where the employees were hired with the understanding that their employment was limited to the duration of the project or undertaking.
Keep in mind, federal WARN Act requirements may still apply.