You can also find polyester thread from the majors (Coats and Clark?) at some fabric stores which is labeled as treated to resist UV, and in more than one color.
Don't strip this, mods, as off-topic, for asking here why I cannot safely hand-sew with heavy- weight nylon, the only heavy thread I was confident one night at Walmart did not have some cotton in it. I understand nylon is not to be used in machines by those who have not set up their machines for the properties of (stretchy) nylon. Nylon thread bad? I thought there was a claim it swelled a little when wet, self-plugging stitch holes.