Unseasonably warm weather in parts of Russia is causing snakes which normally become dormant in late September to remain active, experts have said.

November has been 5.5 Celsius degrees warmer than normal with daytime temperatures in Moscow rising up to 11 Celsius (52 Fahrenheit) degrees, according to Alexander Varentsov, a meteorologist at Yandex Weather.

That has meant the sun continues to warm the forest floor where snakes usually spend the winter.

“Snakes are less active in winter. But their behavior is focused on finding warm places. If the sun comes out, snakes wonderfully feel where darker patches of soil, stones, protruding snags are," said Alexei Sokolov, a senior researcher at the Scientific and Educational Centre for Biopsychological Research.

Due to global warming, the average temperature in Moscow has risen by 3 degrees Celsius over the last 33 years, according to Russia’s Central Office for Hydrometeorology and Environmental Monitoring.

"There is a chance that this autumn will become the warmest ever measured in Moscow," Varentsov said.

Snakes go dormant in lasting subzero temperatures, which usually happens overnight in the Moscow region in late September or early October.

Vipers, grass and smooth snakes inhabit this part of the country.

Herpetologists say that they might be more aggressive now, because their natural rhythms are disrupted.

It could be doubly dangerous because nature enthusiasts don’t already expect to encounter the reptiles in the woods this time of the year.