For hot weather plants like tomatoes, you might instead ask whether there is an advantage to setting out plants early. Even though we are having warm days, nights are quite cool, soil is cool, and probably tomatoes will do little growing until the soil and air warm up. Although we're all anxious to set out plants like tomatoes, they really won't grow much outside and could possibly be frosted in the next couple of weeks. Regardless of the potential for frost, I'd say Memorial day is a better time to set out hot weather plants.

They usually say Mothers day.