Interestingly enough, according to the Farmers' Almanac, the season will actually kick off with a number of rain storms, "especially [in] areas east of the Mississippi," that will then give way to warm temperatures all around the United States.
"Thunderstorms will announce the official start of summer in the Northeast with heavy rains possible from June 20-23 in the Northeast and Ohio Valley regions," reports the publication's website. "Showers and thunder will welcome the summer solstice in the Southeast, North Central, and South Central areas. Hot and dry conditions are expected on the West Coast."