The warmer, sunnier parts of a country or continent, especially the southern United States, are sometimes referred to as thesunbelt.
During the last recession, migration to the sunbelt accelerated.
Sunbelt in British English
(ˈsʌnˌbɛlt)
noun
the southern states of the USA
Sunbelt in American English
(ˈsʌnˌbɛlt)
US
that part of the U.S. comprising most of the states of the South and the Southwest, characterized by a warm, sunny climate and regarded as an area of rapid population and economic growth