A brutally cold high pressure system from Siberia tightened its icy grip on Central Europe on Monday, as temperatures were poised to plunge below -20 degrees Celsius later in the week. “The cold snap’s ‘highpoint’ is likely to be on Friday. The rest of the week will simply be frigid,” the German weather servive said. The eastern parts of Germany early on Monday were already hit by the Russian deep freeze, with temperatures hovering below -10 degrees. The cold air coming in from Siberia has already caused more than 30 deaths across Eastern Europe.