Average temperatures in Siberia were 18F above average last month, the United Nations weather agency warned Friday.
The spate of exceptional heat has fanned devastating fires in the Arctic Circle and contributed to a rapid depletion in ice sea off Russia's Arctic coast.
"The Arctic is heating more than twice as fast as the global average, impacting local populations and ecosystems and with global repercussions," World Meteorological Organization secretary-general Petteri Taalas said in a statement.
He noted that Earth's poles influence weather conditions far away, where hundreds of millions of people live.
WMO previously cited a reading of 100.4F in the Russian town of Verkhoyansk on June 20, which the agency has been seeking to verify as a possible record-high temperature in the Arctic Circle.
It comes as fires have swept through the region, with satellite imagery showing the breadth of the area surface.
The agency says the extended heat is linked to a large "blocking pressure system" and northward swing of the jet stream that has injected warm air into the region.
WMO said information collected by the US National Snow and Ice Data Centre and the US National Ice Centre showed the Siberian heat wave had "accelerated the ice retreat along the Arctic Russian coast, in particular since late June, leading to very low sea ice extent in the Laptev and Barents Seas".