Weatherproofing coax connections
Water can get into boxes unless they have double O-ring water tight gaskets. There may be some around.

I prefer 3M Temflex™ 2155 Rubber Splicing Tape, but there is also  Scotch® Super 33+ which has a PVC backing for UV protection as an additional layer.

Carefully pry away with a pointed 1-edged razor knife to easily remove it.