Geography and urban development of Dresden temperatures are almost the same as those in cities in southwest Germany; on average 10.2°C per year. In hot summers, Dresden is between the hot Lusatia and the milder Ore Mountains. Both regions are characterised by strong winters: temperatures of −20°C are not impossible in Dresden. The driest months are February and March, with precipitation of 40 mm. Spring months have often been arid in the last couple of years (with less than 10 mm of precipitation). The most precipitation falls in July and August, at 60 mm per month. Due to its location on the banks of the Elbe
Accession of Hamburg to the German Customs Union (Zollverein) Instead of the old international treaties, a constitution bound the states together and solidified the union. Thus the fears of the Hanseatic cities had become groundless. But now it became clear that the other grounds alone were strong enough to keep them away from the Customs Union. Following the Second Schleswig War of 1864, Schleswig and Holstein became a Prusso-Austrian condominium, with Prussia occupying the former and Austria the latter, but on 8 June 1866, Prussian general Von Manteuffel crossed the river Eider into Holstein, which bordered Hamburg on the north. Having warned Austria he was exercising Prussia's condominate right