Denmark uses six time-zones. These six time-zones are observed by Denmark and its autonomous constituent countries: Greenland and the Faroe Islands.
The six time-zones observed in Denmark and its autonomous constituent countries are Central European Time, Western European Time, Greenwich Mean Time, East Greenland Time, West Greenland Time, and Atlantic Time.
The Central European Time is used in Denmark, excluding the Faroe Islands and Greenland. The Faroe Islands observe the Western European Time. The Greenwich Mean Time is used in Greenland’s northeast coast. This area is largely unpopulated, except for Danmarkshavn, which is a weather station, and a few other settlements.
The settlement of Ittoqqortoormiit, Neerlerit Inaat and the surrounding areas on Greenland’s east coast use the East Greenland Time. West Greenland Time is used along the West Coast, including Nuuk, the capital and largest city in Greenland, Qaanaaq, Qaqortoq, Ilulissat, and Kangerlussuaq. Thule Air Base, which is the northernmost base of the United States Air Force and is located on the northwest side of Greenland, observes Atlantic Time.
Barring the northeast coast of Greenland, the rest of the island uses daylight saving time. The transition dates are as per the rules of the European Union. However, Thule observes the United States transition dates. Every year, the daylight saving time begins on the last Sunday in March and ends on the last Sunday in October.