More than 4,000 cities all around the world will switch their lights off on March 26.
The most successful flashmob in history, the Earth Hour, is expected to draw attention to the problems of global warming.
Moscow will support the action with lights going off in the city’s buildings at 8.30 pm on Saturday. Among the participants are Luzhniki stadium, several bridges and the Kievsky railway station.
Earth Hour dates back to 2007 when 2.2 million people in Sydney turned off their lights for just one hour.
What started as a one-city event has become a global movement – a year later an estimated 50 million people were involved.
This weekend Russians are also changing their clocks, putting them forward by one hour at 2am on Sunday.
Under a presidential decree they will not be put back in October, so Russia will remain in non-stop summer time.
Medvedev based his decision to cancel daylight-saving time on studies suggesting the switch puts a strain on public health.