I live in Florida too and my chickens have been fine when it has come to that temperature. I'm sure they will be fine, they have feathers and that keeps them warm.
Wow! Thanks so much for all your responses. Guess 45 degrees is no big deal. I have a grown RIR and two young Dominiques. I'm just so used to warm weather, I figured they were too. They have a nice coop at night to sleep in with three windows for ventilation, I partially close them but there is still airflow.
Your birds will be fine. We routinely get into the -20's here in winter. Some can get a bit shocked from sudden drops, but I personally have never had a problem.
Generally you will see your birds hunch up, maybe stand on one leg, stand close together, and even shiver. It doesn't mean you need extra heat. It's all the ways they warm back up. Adding extra heat will mess with the natural acclamation process where the bird gets used to cooler temperatures, and the coat thickens up.
Nature has provided chickens with a warm coat, and the ability to regulate their own body heat. Your job is to provide a good fresh ration, fresh clean water, good roosts, wind breaks, protection from the elements, and good ventilation, as well as maybe a bit of scratch to get them moving and scratching which also warms them up, and allows you to check that everyone is doing okay.
Third Ohio opinion, your birds will be ok as long as they are not in a draft.
Bought a heat lamp with red heat light, and hooked it up to a thermostatic controller so it will turn on and off at certain temps. Set it to turn on at 15 F. Will turn off at 20 F. I’m confident my chickens will be ok. I wasn’t going to add any heat, but rest of family wanted it, and we can get to -18 or so in the coldest part of winter, with some days never out of single digits at the high temps, so that is why I agreed to some heating.
They've been naturally and gradually acclimating to the cooling temperatures already, so a dip into the 40's is nothing for fully feathered, mature Florida birds. As all of the previous posters in the cold climates have said, chickens do just fine in even colder temperatures.
I'd add that in my experience; compromised birds, bullied birds, old birds and young, inexperienced birds "may" require closer attention to make certain they access to the necessities like food and water. Without...expect birds to be susceptible to cold temperatures; they can freeze extremities and succumb quite quickly. I have a few older/special needs birds I supervise everyday until I relocate my older guineas.
As others have stated, chickens are incredibly resilient and can handle cold weather surprisingly well. We get as cold as -36C (-32.8F) and as hot as
35C. (95F) Certainly not the hottest or coldest place, but we can drop from 0 C to -24 C, we just did. I'm the only one suffering because I haven't got my winter gear out yet.
I"m in central Florida and have been concerned as well. My birds are about 5 months old now and while I know that they should be ok, the drastic change in temperatures was more what I was most concerned about. Thanks for the info!
40 degrees is nothing. We have temps in the teen right now and sometimes single figures and below zero frequently in the winter in Michigan, and my chickens do fine without a heat lamp.