Trick-or-treaters face a -4C Halloween night in parts of Britain ahead of a washout weekend and a risk of snow toward the end of next week.  Sub-zero temperatures will hit tomorrow, with chilly but sunny spells across the north-east of England while the south-west suffers showers. And heading into the evening, fog will add an eerie quality to those heading out for spooky celebrations on October 31.   Temperatures are set to plummet tonight before Halloween sees temperatures as low as -4C, with fog expected to add an eerie feel to Halloween  Milder Atlantic air will start to move in on Friday, meaning that the country will experience warmer weather, but snow is expected toward the end of next week  It’ll be a chilly and foggy night for those who are heading out on trick-or-treats to celebrate Halloween as temperatures are set to fall below -4C (file photo) The Met Office predicts increasing clouds through Wednesday with intermittent rain in the west, and much the same on Thursday. Heavy rainfall is forecast for Friday, though the temperature will be milder. Persistent rain last week led to several football matches being cancelled, train delays and rivers bursting their ban...