What temperatures and humidity levels can a telescope handle?

[laban77]

Today it's about -16 outside. On extreme winter nights it can get as low as -30 degrees ©. In the summer it's usually between 20-25, sometimes up to 30.

I have a 12" dobsonian, and wonder what it would take to build a permanent observatory in the garden. If I would buy one of those domes that are for sale, would it be enough to protect my telescope in all weathers? Wouldn't it still get all frosty in the winter? Or wouldn't it be completely baked in the summer sun?