Definition of "all-weather"

all-weather

adjective
not comparable
1. Not affected by climatic conditions; capable of normal operation regardless of precipitation, wind, sun, etc.
  Quotations
  For China the Aksai Chin serves as a necessary communications link; an all-weather road system goes through there.
  1987, Steven A. Hoffmann, “Ambiguity and India's claims to the Aksai Chin”, in Central Asian Survey‎, volume 6, number 3, pages 33–60
2. (figuratively) Always there when needed, reliable, dependable, loyal, faithful.