Climate of the city
The climate of Tallinn can be described as humid continental due to its location in the transition zone between maritime and continental climates at the coast of the Gulf of Finland. South to south-westerly winds are most common. The average annual rainfall is about 700 mm and is fairly evenly distributed throughout the year, with a small peak in the summer months. From May to September, thunderstorms and convective precipitation become more frequent. During the rest of the year, precipitation occurs mainly as stratiform precipitation in the form of rain or snow.
The summer months are usually mild with an average daytime temperature of 20°C and only rarely temperatures above 30°C. Wind patterns are affected by the sea breeze especially from April to July when days are long, and the sea is colder than the land. During sunny days, this temperature gradient results in wind blowing from sea to land, resulting in lower temperatures near the sea than further inland. Temperature differences between areas near the shoreline and outskirts of Tallinn can be considerable (>5 °C) during such days. The breeze can also cause fog on the shore, especially in combination with warm and humid air masses. In the winter months, average temperatures usually fluctuate between +5 and -10°C. Snowfall typically occurs in the months of November to March, and in cold winters, the Gulf of Finland can be covered by ice. When sea ice is missing, the so-called lake- or sea-effect can be observed during this time, as cold air masses move from the northeast to the southwest over the open, ice-free, and relatively warm waters of the Gulf of Finland, picking up water vapour. This can cause heavy snowfall on the coast, with more than 10 cm of snow falling in a single day. In extreme cases (such as 2010, 2022), 30-50 cm of snow can accumulate over a few days.