The reason is that the heating or cooling capacity of water is much less as compared to land. It means that water takes more time to get hot or cold then land. Therefore areas near sea or ocean have more moderate temperature in the day time and less cooler at night. Coastal areas experience less contrasts in temperature conditions due to moderating effect of the seas. The large water bodies helps in moderating temperature. Water has a higher heat capacity than soil and rock, so the ocean takes much longer to heat and to cool than the land. The sea has a moderating influence on the region close to it. Compared to land, water takes longer to heat and cool. Thus, oceans heat up and cool down slower than the land around them. Cool sea breeze keeps the coastal areas cooler in summer and warmer in winter than places far away from the sea.