Land has a lower heat capacity than water. Winds blowing over the sea warm the land in winter and cool it in summer. The effect diminishes with distance from the sea. This means that the temperature difference between winter and summer is less close to the sea than deep inland. Air masses moving over the sea pick up water and dump it on the land, generally as rain. The amount of moisture available to produce rain reduces with distance from the sea. The British Isles are on the western seaboard of Europe and benefit from the moderating influence of the Atlantic and the Gulf stream in particular. Siberia is a long way inland; itis pretty dry and experiences very big temperature differences between winter and summer