I don't stop watering even then. But mine do get quite cold, outside. Early in my "orchid career" I killed a few nobile-type Dens following the "no water" advice. I have since learned that California "dry" is a lot drier than Asian "dry". Especially, monted plants dry out very fast (My Den hekouense plants are mounted) If potted, you may water less... maybe once a week. But even bare, they do need a little.