Both Ascot and Haydock will have to pass early inspections if they're to hold fixtures on Saturday afternoon.
Ascot, which is set to feature another fascinating clash between El Fabiolo and Jonbon in the Grade 1 Clarence House Chase after both contenders were declared on Thursday morning, will have to pass a 4pm inspection this afternoon in order to race on Saturday.
The course remains frozen in places after temperatures reached as low as minus 6C on Wednesday night, with the Berkshire venue also expecting lows of minus 4C on Friday night.
"We were expecting to get down to minus 4C last night, but we actually got down to minus 6C," said clerk of the course Chris Stickels.
"It's still colder than minus 2C now here and the forecast for tonight is for temperatures to get down to minus 4C.
"The course is frozen under the covers and with the forecast we've got, I would imagine we're going to be unable to race. There's nothing at this stage that gives me confidence."
Haydock will have to pass an 8am Friday inspection if they're to race on Saturday, with Clerk of the course Kirkland Tellwright labelling their chance of getting the go-ahead as a 'long shot.'
The course is set to play host to the Peter Marsh Handicap Chase but with temperatures dipping to as low as minus 7C last night, the fixture looks to face an uphill battle.
Kirkland Tellwright said: "It's a long shot but we have got one eye on this thaw.
"We will probably fail to race, but we think it's worth running with it a little bit longer in case that thaw comes a bit earlier than expected.
"We got to minus 7C last night so the majority of the track is frozen, including some areas under the covers, so we have a steep gradient to climb."
Taunton's Saturday fixture will also have to pass a Friday inspection (12pm) if it's to get the go-ahead with the course currently unraceable.