Other than being frozen to death, the cold long term is just like you and me being in freezing temps. More likely to contract illnesses, sluggishness, no interest in food...
Just compare it to you being in 20 degree weather.
Its not fun, its not something you want to be in, but if you have to, you can.
Just don't let it happen again.
Always have a backup plan for your animals. They depend on you.
Oh, you Californians. If it reached 20 degrees here in February, we would declare it a heat wave and take off our coats.