"whitehead1972" wrote:

Mornin' all (again). Today I recorded a minimum temperature of 8.2c on
my Oregon Scientific thermo. My Casella sheathed alcohol thermometer,
however, recorded a minimum of 9c. Is it possible that the grass
temperature can be higher than the air temperature?
The previous night's readings were 6.2c (air) and 5.5c (grass).
The site of the grass minimum is not Met Office standard (my garden's
not big enough) being situated close to a sheltered gravel board fence
and shrubs. The ground make up is imported loam over a clay base.

Yes, it can. In fog, for instance. And after the passage of a cold front
after sunrise but before 0900. Mine was on Wednesday morning.
It will happen more often (and your grass min will be rather higher
than it should be on radiation nights) if the thermometer's 'sky view'
is limited - by shrubs, a fence, or neighbours' trees, for example.

Philip