A sculptor works on a wall of the ice fortress in a park in central Moscow on December 23, 2012.
Temperatures across the capital region were expected to drop to almost minus 30 degrees Celsius (minus 22 Fahrenheit) in the night.
Aside from the 88 people who have perished, another 538 people needed hospital treatment, Russian news agency Ria Novosti said, citing a medical source.
The agency said seven people, including a child, had died in the past 24 hours.
An official with Moscow's education department told the Interfax news agency that younger children could stay home on Monday.
Russia has been in the grips of an intense and unseasonable chill for the past 10 days or so. Temperatures have fallen to below minus 50 Celsius in eastern Siberia, and minus 20 in Moscow.
The temperatures are 12 degrees lower than seasonal norms, with such chills not normally arriving until January or February.
The vicious cold snap has also claimed lives across eastern Europe.
Authorities in Ukraine, which has been battling heavy snowfall for weeks, said Friday that 83 people had died of cold, with 57 of the victims found on the street.
Russian weather services, however, are expecting a warming later in the week.
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