Fortunately, my Warrior (like most or all Piper PA-28 models) has an
outside air temperature gauge with a long metal probe sticking straight
out into the airstream from the middle of the windshield. Because the
probe is so narrow, ice will form on it before just about anything else
(except maybe the antennas, which I cannot see). I use it as my
early-warning device, and divert to warmer and/or dryer conditions as
soon as the first tiny piece of ice forms on the end of the probe.

Don't count on it. I flew into ice in the Blue Ridge mountains; I was
keeping a good eye on that temperature probe and other things sticking
out, but the wings got what I now in retrospect realize was a nice
coating of clear ice while the probe stayed clean as a whistle. Then
all of a sudden the windshield iced up - bang.

I declared an emergency and got vectors to warmer air and an ILS. It
took a while for the ice to come off, but it did before I landed.

Jose
--
Money: what you need when you run out of brains.
for Email, make the obvious change in the address.