It could have been so much colder overnight if it hadn’t been for some low cloud and the wind never really falling out across the north. The 18-06 period is often not the coldest period in autumn and winter, as was the case at Altnaharra this morning when the 07 UTC temperature was -4.0°C and still falling. A distinct warming from -3°C to +3°C on Cairngorm from 03 UTC, maybe it’s milder air above an inversion associated with a layer of SC that’s spreading in from the north, or has someone set a fire under the sensor?