HELSINKI (AP) — Thousands of tourists were stranded in northern Finland on Sunday after flights at Kittilä airport were canceled due to severe cold.

The temperature at the airport dropped to minus 37 degrees Celsius (minus 34.6 degrees Fahrenheit) on Sunday morning, after several days of similar frigid weather, making de-icing of aircraft and other operations difficult, Finland’s national public broadcaster Yle reported.

The deep freeze is expected to continue in Kittilä, which is located in Finnish Lapland in the sparsely populated north, on Monday, when the Finnish Meteorological Institute predicts temperatures of almost minus 40 C (minus 40 F).

Finns are generally used to frosty winter temperatures but this year’s cold, which has affected wide regions of northern, central and eastern Europe, is more severe than in other years.

Heavy snowfall, high winds and icy roads have made travel difficult in parts of Europe.

In Germany, train passengers were still experiencing long delays and cancellations Sunday after rail operator Deutsche Bahn shut down all service in the north of the country on Friday due to strong snowfall.

Authorities announced that all schools would remain closed and switch to online classes on Monday in North Rhine-Westphalia, the country’s most populous western state, after forecasts of icy roads across the region.

In the Baltic countries of Estonia and Lithuania, drivers were asked to postpone all nonessential travel because of expected blizzards, while neighboring Latvia issued a snow alert for the west of the country.

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This story corrects the Fahrenheit conversion.