Warwick to inspect
Friday's meeting at Warwick is subject to a precautionary inspection at 8am.
Temperatures remained above freezing during Wednesday night but a frost is forecast overnight into Friday, with a potential low of minus 4C.
Clerk of the course Sulekha Varma said: "We've very low temperatures forecast but we have covered the whole track in fleece.
"We're confident that can keep the frost out of the ground but the problem is temperatures are not due to be particularly high tomorrow or rise quickly, and it's what happens when we take the covers off.
"We've just got to make sure we are OK when we take the covers off, but we've got until around 11am until we have to do that, so we have time and it's just to be on the safe side. There's no frost this morning, even though one was forecast."