What is Distance from the Coast?
Summer- The land heats up quicker than the sea. The heat is stronger on the land and it is retained for a short while. The sea takes longer to heat but once it is heated it will retain it. Thus, inland areas have higher temperatures than coastal areas.
Winter- In winter the land loses it's heat quickly, but the sea maintains its heat built up from summer. Therefore, coastal areas will have warmer temperatures than the inland.