Racing has been abandoned at Lingfield Park in Surrey after an overnight temperature of minus 5.5 degrees Celsius (22F) made the track frosty, while Benson in Oxfordshire saw a record low this winter of minus 8.1 degrees Celsius (17F).
Elsewhere Bala in Wales saw the mercury drop to minus 6.7 degrees Celsius (20F), and minus 5.9 degrees Celsius (21F) in both Katesbridge, Co Down and Eskdalemuir in Scotland.
Met Office forecaster Mark Wilson said: "We would warn people to be aware really and just be considerate of the fact that there could be some icy patches which are on untreated surfaces like pavements, cycling paths and minor roads."
Conditions are set to get milder into the weekend, with daytime highs of up to 10 degrees Celsius (50F) in southern parts of the UK, he added.
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