"Hot" is a pretty nebulous term. Best I can tell, your warmest temperature during the last several days was in the very low 80’s. That’s not really all that hot for chickens as long as they have some shade. It is only one chicken doing it, not the whole flock. I have a whole lot of trouble believing it is weather related. If low 80’s is considered hot for chickens, most of our flocks won’t make it through the coming summer.
It’s possible something is irritating her throat or respiratory system. It could be allergies, either something she breathed in or something she ate. It’s highly likely it is nothing serious especially if she is acting normally otherwise.
Is her crop swollen and stuffed, not going down over time or overnight? An impacted crop may be partially blocking her breathing passages. Or is she a food hog, overstuffing her crop when she eats?
It is always possible it is something serious, a disease or maybe some type of food poisoning or maybe mold. Keep an eye on her and the rest of the flock. Is there any discharge from her mouth? Do you hear any raspy breathing? If they are acting normally, it is probably not this. If she or another hen starts standing around, fluffed up, and acting lethargic, be more concerned.
Do some research on gapeworm. That’s a parasite that lives in their throat. If you look down her throat and it is unusually red, that could be the problem.
I really don’t want to frighten you, though I probably have. I’ve seen hens do that and they were fine. It is highly likely it is nothing serious but it is something to pay attention to. You were right to ask.