Almost two million people in Russia and occupied Ukraine were left without power on Monday, after hurricane force winds and heavy rains cut electricity lines and caused widespread flooding.
Huge waves crashed over beachside areas of Russia's Black Sea coast, video from social media showed, as wind speeds reached over 140 kilometres (about 90 miles) per hour in some places.
At least four people were killed during the storm, local media said.
Two bodies were found in Russia's southern Krasnodar region, while a sailor was killed in the Kerch Strait between Crimea and Russia, state media reported.
One man on the Russian-annexed Crimean peninsula's southern coast was also killed, according to Oleg Kryuchkov, an adviser to the region's Russian-installed governor Sergei Aksyonov.
"The man went out to look at the waves and, unfortunately, tragically died," he said.
Russia's energy ministry said "about 1.9 million people" were affected by power cuts in the southern Russian regions of Dagestan, Krasnodar and Rostov, as well as the occupied Ukrainian territories of Donetsk, Lugansk, Kherson, Zaporizhzhia and Crimea.
In Crimea, one of the worst affected regions, Aksyonov said rescue workers hoped to restore electricity over the next two days.
Crimean lawmaker Vladimir Konstantinov said on state television that the peninsula had experienced an "armageddon"-like scenario.
"Old-timers can't remember this kind of wind and waves," he said.
- Highways hit -
Parts of Crimea's coastal highway linking the cities of Yevpatoria and Simferopol were closed due to flooding, and ferry services from Crimea's largest city of Sevastopol were suspended.
About 500 marine animals in Sevastopol's aquarium were killed during the storm, which flooded one of its floors, the city's Moscow-installed governor said.
Transport on the Ukrainian mainland and southern Russia were also affected.
Train traffic on Russia's Black Sea coast was disrupted after rail tracks fell into the sea, while oil loading at the port of Novorossiysk was suspended.
Kyiv said more than 2,000 towns and villages were left without power due to bad weather on the Ukrainian mainland, which was hit by up to 25 centimetres (10 inches) of snow.
"In total, 2,019 settlements in 16 regions are cut off from the grid," Ukraine's interior ministry said.
In the southern city of Odesa, which has been subjected to repeated Russian strikes, authorities said they had helped 1,624 people who had been trapped due to snow.
Regional authorities said the temperature had fallen to below freezing with reports of gusts of up to 72 kilometres (44 miles) per hour.
Ukraine's energy grid has been targeted systematically by Russian forces since Moscow's assault began last year, and officials have warned strikes could intensify over winter.
