pipe rolled out from road to pond, page-11

Thermodynamically, the real driver is the surface temperature of the water and the (convective) film coefficient which is basically governed by the air velocity and the temperature of the air.

Water temperatures in the winter would be around ground temperatures which are about 11C in this neck of the woods and in the summer about 19C.

Black plastic helps especially when water level is low by increasing water temperatures (and therefore surface water temperatures).

The evaporative effect causes a net cooling of the water which heats up by absorbing heat from surroundings.