As above. Parrots can't handle quick temperature changes.
Since these are equatorial species, didn't evolve to handle colder temperatures.
When I first got into parrots, the recommendation was 72 f and above. 20 + years later I still stick with that. I now live in north Florida , and I have a radiant heat panel called sweeter heater. I use if ror when temps drop, sick burds, and after baths.
When Temps drop or there are cold snaps, we often hear if a bunch of sick birds or sudden deaths.
That because birds live on such a fine metabolic line, they have a high metabolism, simple quick moving digestive system , and few fat stores, or even muscle stores. Because they evolved for flight , in an abundant food rich environment with stable temperature.
So the sudden temp drops burn extra calories to stay warm , and birds already burn a lot of calories to stay warm due to air sacs . And if they had a hidden health issue this is all to much for them.
I always recommend moving burds cages away from windows in cold temp . My windows suck, and the chill seeps in .
Sure creatures can adapt to a certain point and some better than others. But they do this behavioral ( seek sheltered, or cavities) , by eating more and possibly choosing higher fat foods, and by adoptions our bodies make be it increased red blood cells, increasing fat storage ect...
So your question, is it because you are keeping him outside? Or just a general question?