On Thursday, 24 July 2014 17:20:15 UTC+1, Dave Ludlow wrote:
On Thu, 24 Jul 2014 17:01:11 +0100, Hugh Newbury
wrote:

Early this morning (0450) the humidity recorded by my AWS was 3%, the DP
-29.6.

I think your instrument recording DP failed, or it transmitted/you
received an incorrect value. At 04:50 BST here, air temp was 18.0 deg
C, dew point +14.2 deg C, humidity 78%.

This afternoon I did record my lowest humidity of the year so far,
when the air temp. was 29.6 deg C, dew-point 11.2 deg C, relative
humidity 32%.

Don't dismiss it though. A blip like that might be a resource for geo-physics when the next generation replaces this lot of sheeple.