I live North of Los Angeles and have several types of Orchids out doors all year. I have seen them covered with frost ad on the rare occurance snow for a short time. There are several that grow like weeds outdoors in this area of dry unhumid weather. in the pictures below there are Lealias, Shomburkias, Blc. type hybrids, Dendros, Vandas, Cyms. and several others.