Closer to hatch, watch for an article on when and what to spray. The damage done to fruit blossoms by freezing temperatures will depend upon the stage of the blossom and the actual temperature. As blossoms approach bloom, they become more sensitive to cold damage. However, rain or even snow, can help protect blooms. Unfrozen water on blossoms will protect them until the water freezes.
Snow acts as an insulation barrier to the cold.
So if temperatures drop below freezing for only a short time, damage to fruit buds may be minimal, if any. To check for low temperature injury to fruit buds or blossoms, use a sharp knife and cut them in half. If the tiny seed in the center is white to cream color no damage has been done. But if the seed in several buds or blossoms is dark brown or black, it has been killed. It is possible to give some protection to blossoms from freezing by covering the tree with a bed spread, blanket or similar fabric.