gas gauge/mpg issues

i moved from south carolina up to washington state and obviously it gets a lot colder here, my question is does the weather affects the gas mileage and tank on my 2006 prius??? i’ve noticed the beads on my dash going down a lot quicker (it’s appearing like i’m halfway through my tank at 90 miles even though i‘m not actually) as well as my mpg went from 48 to 43ish. i do need a new catalytic converter so that‘s probably one of the reasons for this issue but im curious if the cold weather affects it too and what i can do to try and preserve my mpg during winter