Moscow on Thursday saw its warmest December day in recorded history, allowing locals and tourists to walk around without heavy coats but preventing bears at the zoo from hibernating.
The warm spell is even coaxing mushrooms out of the ground in nearby forests.
Moscow's meteorological service said Thursday the temperature rose to 50 Fahrenheit, balmy for a city famous for winter snow and ice.
The average winter temperature in Moscow is 24.8 Fahrenheit.
State television reported that bears at the Moscow zoo were unable to hibernate.
Moscow drivers complained about losing the metal studs on their snow tires on the snow-free asphalt.
"Perhaps, these records are related to natural climate changes, but one should not deny human influence on the climate," meteorologist Dmitry Kiktyev was quoted as saying Thursday in the newspaper Komsomolskaya Pravda.
By Sunday temperatures are expected to drop to 32 Fahrenheit.