This afternoon's Fighting Fifth Hurdle meeting at Newcastle is subject to a second inspection at 9.45am after an initial 8am check proved "inconclusive".
Newcastle call a second inspection.
Officials said they were "optimistic that racing will go ahead but need the chance to see it in daylight" before calling the second inspection.
Clerk of the James Armstrong later tweeted: "Sun is rising. We will look again @NewcastleRaces at 9.45am to give temps a chance to lift. Clear skies still & will assist with small areas."
A cold night also means Bangor must assess conditions, with a precautionary look scheduled for 9am.
At Bangor, it was dry and clear overnight, where a cold day is forecast together with the threat of localised freezing fog.
Carlisle is another track to feel the cold, with temperatures dropping to -5C overnight and resulting in a 2pm inspection being called this afternoon for tomorrow's card.
Latest Win Double Tip
|Date||Silk||Selection||Time / Course||Price|
|£10 Win Double Pays £121.88 with Bet365|
|18/08/2017||Global Passion||14:00 Nottingham|