I had a pair of Cat Eye $20ish lights that I used for a very rainy 24hrs of Canaan (back when it was actually in Canaan Valley) and those little buggers worked for many years after that, even after I moved on to bigger brighter lights.

If you were looking to get completely water proof lights Baja Designs Strykr and Strykr Pro lights are both completely waterproof to 33ft - definitely no worries about about rain. The company also has a Trade-Up program for your old lights, $100 credit towards a new Strykr or Strykr Pro, you'd never need to be concerned about rain again

Shannon