Hello, I live in Southern California. I have 2 hens left of my 5. Unfortunately I lost 1 to heat and 2 to respiratory issues. My 2 remaining hens are healthy and happy. They are 8 months old. 1 laying one not yet. My question is about weather. At what temp should I be using a warming lamp? It's not that cold in Cali but when you consider last months high temps of 105 to this months low of 50 degrees that's a big difference in range. Should I be using a lamp?