Probably Bulgaria but it depends on the time of the year and the weather conditions they would be having!
Yes, it is considerably hotter.
Maltar is a country way hotter than Bulgaria.
bulgaria
Something to do with the Equator.
Destiny Chukunyere of Malta won the 2015 Junior Eurovision Song Contest in Bulgaria with the song "Not My Soul".
Vienna, Australia doesn't fit. Lisbon is in Portugal, Sofia in Bulgaria and Vaduz in Malta, but Vienna is not in Australia, but rather Austria.
air flight around 3 hours
Lisbon is in Portugal, Sofia in Bulgaria and Vienna in Austria, but Vaduz is in Lichtenstein.
End of June and beginning of July are hotter period.
Vaduz Malta is probably the one, since the rest of the cities listed are both on the European mainland and are capital cities.
Russia, Solvakia, Croatia, Bulgaria, Lithuania, Latvia, Estonia, Macedonia, Moldova, Malta, etc.
Spain, Portugal, France, Monaco, Italy, Malta, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Albania, Greece, Cyprus, Turkey, and Bulgaria.