I went out for a ride Tuesday using a different pair of overshoes from normal. After 1.5 hours my feet were so cold I called home and arranged someone to pick me up from a car park 10 miles from home (I phoned them when I was still half an hour away so the rest of me wouldn't get cold waiting).
I'm expecting a sudden warm spell, because I took delivery of some winter socks yesterday, and I'm not using those overshoes again (wind went straight through them). I'm also going to run 20 mile laps to get my training mileage up, so I'm never more than 10 miles from home.