Nukualofa doesn't observe daylight saving time but Calgary does. DST in Calgary started on 10 March 2019 and will end on 03 November 2019. Once DST ends in Calgary the time difference between Nukualofa and Calgary will be -20:0 hours.
Time zone: TOT - Tonga Time (UTC/GMT +13)Time zone difference / Flight distance
Time zone: MDT - Mountain Daylight Time (UTC/GMT -6)DST started on 10 March 2019DST will end on 03 November 2019Time zone difference / Flight distance