Pleasant W or WSW breeze &
temperature at 09Z was already 20.2degC (the 24hr max for the 26th).

This is one of the problems with a 24-hr max/min. I use 12-hr (08Z and
20Z) max's and min's, which would have avoided this particular anomaly, but
causes others, such as missing a night-time max or early evening min, nearly
always in winter. But one has to stick to one's declared régime however daft
it may occasionally seem.
Minimum overnight here 14.9°C.

Tudor Hughes, Warlingham, NE Surrey, 556ft AMSL