Taunton's richest ever meeting on Saturday could be the best chance of any turf racing going ahead over the next few days.
Temperatures in Somerset are fairly tropical compared to most of the rest of the country, but even they are not completely safe, with a band of either snow or rain moving in.
Taunton groundsman Kevin Council said: "Whether we get rain or snow we'll just have to see as it depends on which forecast you read. It is due to hit us early on Friday so we should know by 10am where we stand."
Ascot's meeting, which features Sprinter Sacre's return in the Grade One Victor Chandler Chase, will need to survive a 4.30pm inspection on Friday, but snow is forecast.
Clerk of the course Chris Stickels said: "There are some signs of frost under the covers. I'm pretty confident we could race (on Thursday) but could not be certain unless I lifted the covers right off.
"Snow is forecast for Friday afternoon and evening, so it makes sense to have a precautionary look on Friday when we'll have a good look under the covers and we'll be able to assess the snow situation."
Haydock's meeting on Saturday, which is due to stage the Peter Marsh Chase and a Champion Hurdle Trial, is in grave doubt, as having already survived one inspection, clerk of the course Kirkland Tellwright will look at 8.30am on Friday.
He said: "We had minus 3C overnight and we are forecast further frosts and there is a clear chance of snow on Friday afternoon. We could get six centimetres of snow and obviously that would beat us, so there is plenty to worry about yet."
Lingfield's all-weather meeting on Friday is also subject to an 8am precautionary inspection on raceday morning due to the threat of snow.
Clerk of the course Neil MacKenzie Ross said: "It now looks like there is now potential for heavy snow over us on Friday. We've dealt with snow in the past, but it could cause a problem if it's continual."
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