Wincanton and Sandown officials have been forced to abandon their Saturday afternoon meetings because of frozen tracks.
Temperatures hit a low of minus four overnight at the Somerset venue and minus six at Sandown despite covers set down to protect the courses.
Clerk of the Wincanton course Barry Johnson said: "We could have taken a minus two or minus three frost but it was down to minus four and a half and that has tipped us over the edge.
"It is not going to improve fast enough this morning so we have no option but to abandon."
Sandown clerk of the course Andrew Cooper was also forced to admit defeat after morning inspections.
"Parts of the track that were okay at 6am have actually frozen this morning and we are still minus four as we speak," said Cooper.
"In the shade on the hill is really frozen so in the end, it actually became a relatively easy call for us as we know this doesn't thaw."
Racing on the mainland will take place on the all-weather tracks at Kempton and Lingfield, while they also race in Ireland at Cork.

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