Hawaii

Hawaii was the location of a relay station for the Snowcap space tracking station. It was known to be in active operation during at least the month of December 1986. (DW: The Tenth Planet)

In December 1999, snow was reported as falling in Hawaii. (DW: Doctor Who)
 * It's unclear that Hawaii has ever been referred to as a state in Doctor Who'' fiction, though it's unlikely that a local American news broadcast would be referring to Hawaii unless it were a state, thus allowing them easy access to weather reports and video footage.