Repeated Russian bombardments of energy infrastructure in and around Kyiv have left the Ukrainian capital with only enough power for about 20 percent of the city’s 3.3 million residents, energy officials say, a situation that is forcing utilities to institute longer and more unpredictable outages to keep the grid stable.

“Ten hours without electricity in Kyiv is, unfortunately, a new reality,” Serhii Kovalenko, the head of the local utility, Yasno, said on Monday night.

In the latest wave of Russian attacks on Monday, the Ukrainian Air Force reported that it had shot down 30 of about 35 drones aimed at targets around the country, but Mr. Kovalenko said that a critical piece of infrastructure in Kyiv had been hit. That strike knocked out power for homes and businesses on the right bank of the Dnipro River, which runs through the center of the city.

All of the city’s critical infrastructure has power, he said, including hospitals, water utilities and subways. But officials cannot say when utility operators will be able to provide a reliable schedule of outages, which would allow the capital’s estimated two million wartime residents to better plan their daily lives.

Months of repeated bombardments have left tens of millions of Ukrainians across the country struggling with increasingly prolonged periods without heat, electricity and running water. After each wave of strikes, utility workers race to make repairs, but those efforts become more challenging with each new attack on already battered infrastructure.

As winter grips the country and temperatures plunge well below freezing, the central heating service that warms millions of homes is also under threat. A survey released on Tuesday by the International Rescue Committee, an aid group, found that 25 percent of people forced from their homes by fighting in Ukraine were now living in homes without access to sufficient heating.

Kyiv’s mayor, Vitali Klitschko, said that as a result of the power cuts in the capital, 10 boiler plants did not have reliable electricity, a volatility that is likely to interrupt the heating in 144 residential buildings. President Volodymyr Zelensky said on Monday that each wave of Russian missiles and drones could affect tens of millions of people.

Even before the drone strikes on Monday, a missile bombardment on Friday had knocked out power to over 22 million Ukrainians and left another 10 million without water.