No Russian ships are able to operate in the Black Sea and the Sea of Azov because of the blizzards, giant waves and winds of up to 90mph, Ukraine’s navy and southern army command said.
The brutal weather has been called the “storm of the century” by Russian media after it left at least 18 people dead, 33 injured and millions without power in Ukraine, Russia and Moldova.
One Russian blogger said that naval minefields were feared to be drifting after the storm broke boom nets keeping them in place.
High tides have washed away trenches, coastal barriers and firing positions at Yevpatoriya, a city near the Sevastopol naval base in occupied Crimea.
In October, Russia moved the bulk of its fleet from Sevastopol to Novorossiysk, a base 200 miles farther east, after it was struck by Ukrainian Storm Shadow missiles.
The Institute for the Study of War (ISW) think tank said that the Russian army could face “logistical ramifications” after damage to railway lines in occupied Crimea and mainland Russia.
Video footage showed Russian engineers being battered by sea spray as they worked to repair a line near the coastal resort of Sochi that had almost been washed away.
The think tank added that the storm has slowed the pace of combat because of poor visibility.
Col Oleksandr Shtupun, the spokesman for Ukraine’s Tavriisk army group, said that the number of Russian drone attacks has decreased “by almost six times” because of the weather.
Artillery bombardments are also down by “one and a half times” but attacks by infantry and armoured vehicles are continuing as usual.
“Challenging winter conditions will force both sides to rely more heavily on infantry-led ground attacks in the absence of aerial reconnaissance and artillery correction capabilities,” the ISW said.
It added that Ukrainian forces have used the harsh conditions to secure their positions on the bridgehead on the left bank of the Dnipro river.
Ukraine has been bitterly fighting to hold on to the foothold since special forces took it in October.