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. (TV: The Tenth Planet)

Hawaii was one of the locations where Ben Jackson would have preferred to spend Christmas rather than in Northumberland. (PROSE: Do You Dream in Colour?)

In December 1999, snow was reported as falling in Hawaii (TV: Doctor Who) as the result of 's opening of the Eye of Harmony. (PROSE: Unnatural History)

In 2070, it was threatened by a hurricane, due to damages of the weather control base on the Moon. (TV: The Moonbase)

During a visit to Blackpool in 1985, Peri Brown asked the Sixth Doctor if they couldn't have gone to Hawaii instead. (PROSE: The Nightmare Fair)

Behind the scenes

 * 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, like the one seen on KKBE, would be referring to Hawaii unless it were a state, thus allowing them easy access to weather reports and video footage.
 * The reference to snow in Hawaii being unusual is somewhat difficult to parse, as there is almost always snow on the Big Island of Hawaii every winter.