In article ,
Martin wrote:

Baz provided what looks
like a very useful rough guide, with an ability to adjust for location,
which perfectly answered the question.

The fact it claims to be "adjustable for location" does not mean the
results are accurate. Simple testing shows they are not. According to it,
every listed Scottish city from Highlands to gulfstream warmed West coast,
share identical first and last frost dates; mid Oct and early May.
Ludicrously wrong on all counts. Far from"perfectly answering the
question" it's a useless gimmick.

The Met Office website climate pages group info by region in a
similarly useless way.

I suggest that you look at the Climate FAQ, which won't answer your
question, but may explain why there can be no answer to your question.

First or last frost dates are a nearly completely useless concept
in the UK. Expressed in layman's terms, even the normal variation
is very large, and exceptional frosts can occur at any time, even
in many of the 'warmer' parts of the UK.


Regards,
Nick Maclaren.