Question

why underground water seems to be cool in summer days while it seems to be some what warm in winter season ?

Answer 1

However, during the fall and winter months, there are many mornings when the air temperature is warmer in the late night and early morning hours near the shoreline. That is because the water temperature is warmerthan the air temperature on some occasions.

Answer 2

because there is very high temperatures in summer only on the upper part of the earth so underground water seem to be cool in summer day.