The best time to visit is May through September, when daytime temperatures average in the 70s F/20-25 C, with nights ranging 40-60 F/4-15 C. Despite its northern latitude, Estonia's climate is relatively mild because of its proximity to water. The coldest months are January and February, when temperatures are in the 20s F/-7 to -1 C, although they can drop to -20 F/-29 C. Even in summer, you should take along at least a sweater for the cool evenings.