In the Sayano-Shushenskiy Reserve, a 'second spring' was reported as rhododendron blossomed. Picture: @calypso_232

Is it a freak heat wave or an indisputable sign of global warming? The experts will argue about this but a range of balmy temperatures in October in Siberia certainly begs a few questions: 27C in Altai, 24C in Barnaul, 21C in Novosibirsk, 21C in Tomsk, and 21C in Kemerovo.

In the Sayano-Shushenskiy Reserve, a 'second spring' was reported as rhododendron blossomed, evidently tricked by the Indian summer into thinking it was May or June again.

Pulsatilla, globe flower, bird cherry tree rhododendron are blossoming as if nature's clock thinks it's mid-May. Pictures: Sayano-Shushensky Reserve, Ekaterina Shishkova, @alexanovo

Pulsatilla was also bursting into flower recently, a certain sign in Siberia that spring is arriving, except that it's October here in the northern hemisphere. In the Republic of Buryatia, wild apple and bird cherry trees are in bloom, as if nature's clock thinks it's mid-May.

Despite this unseasonable warmth, in Norilsk the thermometers hit a familiar minus 14C, yet elsewhere many Siberian cities reported significantly warmer than average temperatures.

'What the hell is going on?' asked one seasoned observer of Siberian climatic rhythms. 'Mid-October is a time when the snow 'lies down', which means that the ground is frozen enough to stop melting,' she explained. Not any more it seems.

'What the hell is going on?' asked one seasoned observer of Siberian climatic rhythms. Pictures: @ioanna88, Anna Shivokhina, Svetlana Krivosheina, Violetta Propishina

Elsewhere, the level of Lake Baikal - which contains 20% of the globe's unfrozen freshwater - is seen as worryingly low. This summer, as in all recent summers, wildfires have raged across huge tracts of Siberia, notably in Buryatia and neighbouring Irkutsk.

In the north, the permafrost melts, unleashing greenhouse gases frozen for millennia into the atmosphere. In the Arctic, the ice recedes more than at anytime in living memory...