I have used various phone cord like connections to some rain gauges on my roof peak, and have had no problem with the wires IF they are the UV resistant type of insulation. I did have some satin 8 conductor flat cable that after a year or so became 8 separate wires flopping in the breeze, on my tower where sunlight was supposed to be minimized by placing the cable on the north face of one of the legs.
All I can say is that the black UV wire is supposed to be good, and the temperatures reached won't be high enough to be of concern, from my experience.
As far as varmints attacking the wire, that's another story. Squirrels are a particular bane of mine, but not on wire.