This is weird.
A nearby weather station to me has recorded three air frosts this December; -0.4°C on 5th, -0.1°C on 6th and -0.7°C on 10th, in a location 2 miles from me and same elevation, just more exposed.
However, in my back garden, which obviously isn't so exposed and has a micro-climate of its own, there hasn't been a single air frost on my weather station yet, and my minima are running a degree higher overall. Ha.