It might not be in most of the country but here in Las Vegas the heat is comming on. When I got out of the hospital and put on O2 24/7 with stage 4 it was late September and cooling down. Besides I was indoors almost all of October and by the time I started going out in November it was cool. Now that the heat is comming on I find my saturation level about the same but I sure get SOB a lot quicker. Why is that? It's hard for me to stay inside. The only tips I know is stay hydrated and in the shade as much as possible if you do go out. Any other breathing tips from anyone out there ? Thanks.