"Adrian D. Shaw" wrote in message
...
Well, the forecasters seemed quite sure about this. But after a not
particularly warm day (since 8am max 11.3C*) the temperature is now
plummeting, along with the dewpoint as the skies clear completely. There
is absolutely no wind and it just feels like a typical late autumn frost
night coming on.

Temperature now (5:18 pm) 8.1C.

*Strangely, the LOWEST temperature to 7am was 12.5C, a very mild night)






Using McKenzie:

http://homepage.ntlworld.com/booty.w...orecasting.htm

With your max 12 and dewpoint 6 gives 9-k


Theres a 35 kt gradient wind and showers downwind of you.

You would need dead calm (very rare) all night to get an air frost.