"Bad weather" as in rain is not a problem. The problem is snow and ice. Tesla's technology comes from Mobileye inc. http://www.mobileye.com/ Tesla's technology and Google's technology do not work in snow and ice. It will work at night and in many rainy conditions although glare can cause problems at night in the rain. The sensor's depend on seeing painted lane markers, which may be difficult when there is glare from light in the dark in the rain.