Freezing temperatures are spreading across Europe, with snow forecast from Germany to the UK, testing energy systems in a second winter without the bulk of Russian fuel supplies.

Berlin is set for a low of -4.5C on Tuesday and Wednesday, while Helsinki won’t get above -8C on Monday, according to forecaster Maxar Technologies Inc. Weather warnings have been issued for some areas of Germany today, where the nation’s meteorological agency expects as much as 20 centimeters (8 inches) of snow.

Parts of Scotland and northeast England will also experience snow on higher ground, with wintry showers spreading south over the week, according to the UK’s Met Office. London will fall below zero by the weekend.

Icy weather is taking a grip on Europe after a delayed start to the heating season that allowed many countries to accumulate record inventories of natural gas to shield themselves from potential supply disruptions. While the fuel reserves are not designed to meet peak winter demand in full, they are helping in keeping prices in check even though some withdrawals have already started.

Weather forecasts after first week of December vary. Maxar said in its daily report that “a cold pattern remains the favored outcome” for most of Europe for the next two weeks, while some models point to a potential rebound in temperatures in the northwest from Dec. 6.

Data from the Global Forecast System offer “warm risk in central and southern Europe, even hinting at above normal temperatures in France and Iberia,” according to Maxar.