He said: "We got down to minus 2C and we were at that temperature for most of the night.
"I thought the frost had got a bit worse from when I walked the track at 6am and with temperatures slow enough to rise today, we're not sure we'll be raceable later on today.
"It's very disappointing but we thought it was fairer to everyone to make a decision rather than delay."
With Newbury already called off, there will be no jumps racing in Britain for a second day.
Thursday's National Hunt action hinges on an 8am inspection on raceday at Wincanton ahead of their Somerset National meeting, with Ludlow cancelled following an inspection on Wednesday morning.
Officials at Ludlow report the track to be frozen in places with further frost forecast.
Newcastle's Thursday card was called off on Tuesday for similar reasons.