Is underground water hot in the winter and cold in the summer?
Seasons do not greatly affect underground water sources.
Underground springs that bring melted snow water underground to a surface source are cold even in the middle of summer. The ground insulates the water that entered the aquifer at cold high altitudes keeping it cold regardless of air temperatures.
Underground springs, known as hot springs, get their heat by contact with the heated magma underneath the earth's surface. This hot springs will be close to boiling hot even in the middle of winter when there is snow on the ground.
The temperature of underground water sources depends on the source of the water not the air temperatures.