First air frost of autumn

The thermometer dropped below freezing for a couple of hours around dawn with a minimum of -0.1C. This is the first air frost to occur in autumn 2014, being as late as 4th November
The incidence of the first air frost in autumn has been, on average, getting later over the last thirty years. This is the second latest since my records began in 1984. My records for the 1980s show the first air frost always occurred in September except in 1986 when it was later on 7th October.
A full analysis showing how, on average, this event has moved later in the calendar over the last 31 years will appear in the next few days.