Winter temps hover around 50 at night in the here in LA. SOBE said they grow it without extra heat in the winter. I would guess winter temps for them is about the same as for us.
The last time I was at the SBOE, a man who works there said that their vandas are pretty hardy because they took temps down to 28°F one winter night. I was surprised, but he explained that their plants are exposed to winds that come from the mountains nearby, instead of from the ocean, which is what I had assumed. I don't think they were out where frost could settle on them. I always have interesting conversations with the people who work at the SBOE.