Estonia lies in the northern part of the temperate climate zone and in the transition zone between maritime and continental climate. Because Estonia (and all of Northern Europe) is continuously warmed by maritime air influenced by the heat content of the northern Atlantic Ocean, it has a milder climate despite its northern latitude.
The Baltic Sea causes differences between the climate of coastal and inland areas. Estonia has four seasons of near-equal length. Average temperatures range from 16.3 °C (61.3 °F) on the Baltic islands to 18.1 °C (64.6 °F) inland in July, the warmest month, and from −3.5 °C (25.7 °F) on the Baltic islands to −7.6 °C (18.3 °F) inland in February, the coldest month.
Estonian Meterologigal and Hydrogeologigal Institute: click here
Weather.com: click here