Decisions, decisions
@Hentherapist
Well, last winter, I would have said they do fine in cold weather, but don't like trekking in the snow. This winter I will say, they still don't like trekking in the snow and they do fine in SUB-ZERO temperatures, with WIND CHILL ADVISORIES into the NEGATIVE 20's for consecutive weeks - even if they decide to ROOST OUTSIDE in a tree for TWO nights!!!!
Yes, I had one do that this year.... I thought for sure she would be dead by the second morning. No food or water for about 48 hours in severe EXTREME cold weather conditions. She would not come down no matter how hard I tried, but fortunately, she finally huddled on top of the wire roof of the run and I was able to get a ladder and detach the roof. The weight of her caused the roof to sag, making a hole for her to fly through and into the coop. Big relief!
I would say they become acclimated to whatever weather they have. If I had transplanted one of your guineas from Texas and left it to roost in a tree for two nights in sub-zero temps, I don't know if it would have survived. If I transplanted one of mine to Texas this summer in your heat, it would probably be stressed. Mine start to show signs of heat stress at about 75 degrees and above, while guineas raised in warmer weather do just fine into the 90's.
So in summary, I worry less about the temperatures than I did last year and everyone, usually, is cooped up at night in a draft free structure, safe from predators. I am finding that they eat more food and I have to change out water more often in two of the coops without electricity. In the extreme cold, I do use warm (not hot) water and add some Nutri Drench just as a little energy boost and I provide some dried meal worms, just a sprinkle on top of their feed.
I know what you mean - last year it was my first time with guineas and I worried about EVERYTHING. Also, I do have an enclosed oil radiator heater and may put that on once in a while in my small barn - more to keep it from feeling damp than anything else. Plus it's a bigger area and their body heat doesn't seem to keep it as warm as my smaller coops. I have thermometers all over the place, inside, outside... I don't think they really need the extra heat; I guess it's my peace of mind.
So, your guineas may not need the extra heat, but if it gives you peace of mind and you decide to add a heat source, I'd recommend something like an enclosed oil radiator heater or infrared bulb just for safety. Fires can happen quickly and a safer source of heat is best. I wouldn't overdo on the heat, again they tend to acclimate to the weather, and keeping them extra warm can cause more problems than allowing them to acclimate. But if it's going to be a big drop and will shock their bodies a bit, throwing on a little heat can't hurt.
Keep warm and good luck! Looking forward to hearing from you again soon. Happy New Year!