The climate is a very important factor of acclimatization; it would be more correct to speak of microclimate, because what most interests us is the climate of the city where we will live.
Broadly speaking we can say that there are three groups.
The first group, with Poland and Romania, has a continental climate and colder weather than northern Italy. In Bucharest, the temperature (min / max) goes from (-6°/2°) in January to (16°/29°) in July, with rainfall not too abundant and widely distributed in the year. Slightly milder the coast of the Black Sea in Constanta, where the temperature is 2°-3 ° higher in respect of Bucharest and especially incorporate many less rainfall; the sea temperature allows bathing in July and August.
The second group, including Slovenia and Bulgaria, has a climate comparable with the north of Italy that in some areas becomes more temperate and similar to that of Venice and Rimini. As an example we take Sofia, passing from temperatures (-5°/2°) in January to (14°/26°) in July and August; rainfall is not abundant. More mild and dry the Black Sea coast, called Sunny Beach, with Varna passing from (-1°/6°) in January to (18°/27°) in August; you can bathe in July and August, with a water temperature of 24°.
The third group consists of Portugal and the Canary Islands. Portugal has a climate similar to that of southern Italy but with a higher frequency of rains in the fall and winter. As a whole it is very pleasant: Lisbon passes from (8°/15°) in January to (19°/28°) in August, with rainfall of 710 mm/year in 79 days. The Algarve has a Mediterranean climate, with a nice temperature range (9°/15°) in winter and (20°/28°) in summer, little rain and plenty of sunshine; the ocean water is not hot though (21° in August).
Finally, the Canaries! Mild weather and temperate all year round, never too hot, never too cold: in Las Palmas temperature is between (15°/21°) in winter to (21°/27°) in summer. Ideal for those seeking the eternal spring. Of course, even in this climatic heaven there may be some inconvenience, as when the Saharan winds blow bringing the temperature even up to 40°, but these are quite rare events that do not disturb the attractiveness of the islands.
An interesting website to explore is Climates and travel, from which we took a lot of information of this section.