This clear silicone adhesive is the best for any type of job that you need to make water resistant or just need sealed up from the elements. This is a good all purpose type of outdoor sealant. I originally got this from a big box store and have used this for a variety of uses as it works on about any surface including glass, metal, and plastics, among other things. This also works well at protecting and repairing electrical wiring and sticks to most surfaces.  Being silicone it is waterproof and is easy to apply and mold to spot you need to apply it on.  According to the instructions this is capable of extreme temperatures, -75F to 400F, although I can't say I have tested the cold extreme but I have used this on wiring that is subject to extreme heat in an engine area and it has worked well for that in addition to areas subject to the hot summer sun.  Being silicone this resists water penetration and weather pretty well.  This dries quickly and leave a good seal after.