So constructed or protected that exposure to the weather will not interfere with successful operation. Rainproof, raintight, or watertight equipment can fulfill the requirements for weatherproof where varying weather conditions other than wetness, such as snow, ice, dust, or temperature extremes, are not a factor.
Merriam-Webster Online Dictionary
weatherproof (adjective)able to withstand exposure to without damage or loss of function - weather
weather-resistant, climate-proof, stormproof, waterproof, durable