Tenants notice: 30 or 60 day?

[Rich Bergstrom]

On May 27 my California tenant gave me notice that they will move out by July 2. They have been in the place 5 ½ years and are paying month to month. However their signed lease says they have to give a 60 day notice. Does anyone know, in California if they have honor the 60 notice if it is in their contract, or 30 days is the law? If the 60 days presides, this would put them responsible up to July 27.

Thanks,

Rich