Temperature in Denmark. Denmark is in the North Temperate Zone and has an average temperature of 7.7˚C (46˚F). February tends to be the coldest month, with average temperatures of 0.0˚C (32˚F), whereas August tends to be the hottest month with average temperatures of 15.7˚C (60˚F).he best time to go swimming in the waters around Denmark is during the summer months of June to August, with average sea temperatures of between 17˚C (63˚F) and 22˚C (72˚F). In August, the average sea temperature can reach 25˚C (77˚F). Winter bathing is also a growing sub-culture.