Saturday's meeting at Navan is subject to a 7.30am inspection tomorrow morning due to a covering of snow on the track.
The course is currently unfit for racing.
Brendan Sheridan, IHRB clerk of the course said: "Following significant snowfall overnight, the track at Navan is unfit for racing at the moment. There was 20mm of rain throughout the day yesterday so prior to the snow the ground was soft to heavy. Temperatures are to rise throughout the day today.
"However, temperatures are to drop again this evening and could get as low as -3C tonight so we have called an inspection for 7.30am tomorrow morning to determine our prospects of racing."
Saturday's Betfair Imperial Cup meeting at Sandown will need to pass an 8am inspection if it is to go ahead as scheduled.
Racing took place at Sandown on Tuesday, but persistent wintry showers since have eased conditions significantly and clerk of the course Andrew Cooper admitted the track would have "struggled to race" on Thursday.
With further rain forecast and temperatures set to dip below freezing on Friday night, Cooper has called an inspection for raceday morning, with the track in a "difficult situation".
He said: "It's clearly a case of taking stock on Saturday morning, but the immediate issues and concerns here would be rainfall and the wetness of the conditions here after the week we've had.
"We raced on Tuesday and the rain started in this neck of the woods after a long break without rain on Tuesday morning. We've now had the best part of 30 millimetres, so over an inch of rain, and there could be a bit more rain later today."
With two inches of snow on the track, officials at Leicester had no option but to abandon Friday's card, but there was better news in Scotland, with racing at Ayr given the go-ahead.
Ayr is also due to stage a Saturday fixture, which is subject to a precautionary inspection at 8.30am due to a forecast of overnight temperatures dipping to as low as -3C.
Friday’s all-weather meeting at Wolverhampton must pass a third morning inspection at 11.30am, while Saturday’s jumps card at Hereford was abandoned following a 9.30am inspection.
