Список поддерживаемых часовых поясов
PHP Manual

Америка

Америка
America/Adak America/Anchorage America/Anguilla America/Antigua America/Araguaina
America/Argentina/Buenos_Aires America/Argentina/Catamarca America/Argentina/ComodRivadavia America/Argentina/Cordoba America/Argentina/Jujuy
America/Argentina/La_Rioja America/Argentina/Mendoza America/Argentina/Rio_Gallegos America/Argentina/Salta America/Argentina/San_Juan
America/Argentina/San_Luis America/Argentina/Tucuman America/Argentina/Ushuaia America/Aruba America/Asuncion
America/Atikokan America/Atka America/Bahia America/Bahia_Banderas America/Barbados
America/Belem America/Belize America/Blanc-Sablon America/Boa_Vista America/Bogota
America/Boise America/Buenos_Aires America/Cambridge_Bay America/Campo_Grande America/Cancun
America/Caracas America/Catamarca America/Cayenne America/Cayman America/Chicago
America/Chihuahua America/Coral_Harbour America/Cordoba America/Costa_Rica America/Cuiaba
America/Curacao America/Danmarkshavn America/Dawson America/Dawson_Creek America/Denver
America/Detroit America/Dominica America/Edmonton America/Eirunepe America/El_Salvador
America/Ensenada America/Fort_Wayne America/Fortaleza America/Glace_Bay America/Godthab
America/Goose_Bay America/Grand_Turk America/Grenada America/Guadeloupe America/Guatemala
America/Guayaquil America/Guyana America/Halifax America/Havana America/Hermosillo
America/Indiana/Indianapolis America/Indiana/Knox America/Indiana/Marengo America/Indiana/Petersburg America/Indiana/Tell_City
America/Indiana/Vevay America/Indiana/Vincennes America/Indiana/Winamac America/Indianapolis America/Inuvik
America/Iqaluit America/Jamaica America/Jujuy America/Juneau America/Kentucky/Louisville
America/Kentucky/Monticello America/Knox_IN America/La_Paz America/Lima America/Los_Angeles
America/Louisville America/Maceio America/Managua America/Manaus America/Marigot
America/Martinique America/Matamoros America/Mazatlan America/Mendoza America/Menominee
America/Merida America/Mexico_City America/Miquelon America/Moncton America/Monterrey
America/Montevideo America/Montreal America/Montserrat America/Nassau America/New_York
America/Nipigon America/Nome America/Noronha America/North_Dakota/Beulah America/North_Dakota/Center
America/North_Dakota/New_Salem America/Ojinaga America/Panama America/Pangnirtung America/Paramaribo
America/Phoenix America/Port-au-Prince America/Port_of_Spain America/Porto_Acre America/Porto_Velho
America/Puerto_Rico America/Rainy_River America/Rankin_Inlet America/Recife America/Regina
America/Resolute America/Rio_Branco America/Rosario America/Santa_Isabel America/Santarem
America/Santiago America/Santo_Domingo America/Sao_Paulo America/Scoresbysund America/Shiprock
America/St_Barthelemy America/St_Johns America/St_Kitts America/St_Lucia America/St_Thomas
America/St_Vincent America/Swift_Current America/Tegucigalpa America/Thule America/Thunder_Bay
America/Tijuana America/Toronto America/Tortola America/Vancouver America/Virgin
America/Whitehorse America/Winnipeg America/Yakutat America/Yellowknife  

Список поддерживаемых часовых поясов
PHP Manual