What about the frost?

This autumn, so far, has seen a couple of white grass frosts (in October) but no air frosts have occurred. How unusual is that? At this site records began in 1988 and since then there have only been 2 instances where the autumn months, September, October and November, have been completely free of air frosts. The years in question were 1994 and 1999. In 1994, November was exceptionally mild and currently stands as the mildest November in this area since before 1900. Also the temperature difference to the next mildest (1938) is, in statistical terms, quite substantial. However, at the moment, this November is milder than that of 1994, also by quite a significant margin. Today may help to change that, though, with the maximum temperature struggling to achieve double figures. In both 1994 and 1999 the frost-free period did not extend through the remainder of the year. In 1994 the first frost of the 'winter' occurred on December 15th with the 14th seeing the first frost in 1999.