Both of my dogs (a golden retriever and an english cocker spaniel) do this (though the cocker may be copying the golden as she does with most things). Temperature doesn't really matter--they rush into the ocean (northwest, very cold), lakes, streams, but HATE getting their bath. The golden will break through the ice on lakes or streams and lay in the water...

Of course, the cocker also, although she WILL BE IN any body of water, large or small, in the vicinity, hates to go outside to potty if it is even sprinkling (which is a bit of a problem as it rains alot here...).

I think part of it is they don't like getting water in their faces. Or, they just like being in control...

Jake's mom