My guess is that it was the outside temp reading,
and when it encounters ambient outside temps
falling to/through 37 degs. F, it beeps 3 times.
That 37 or less, is the magic number for potential
of ice/slickshit forming on highways.
GL,md
PS: all that kind of good stuff is to be discovered
in that marvelous set of books in the black zip case
in your glovebox, aka Da Manual!
PPS: I lived in Warwick, NY next to OldMt.Peter
ski area, from '87 to 2001.