A total of 18 people have died as a result of a period of extreme cold weather in New York City, its mayor has said.

Since late January, the city has endured a cold snap, including 13 days of temperatures of 0C (32F) or below – one of the longest stretches of sub-zero weather New York has seen in six decades.

Over the weekend, another person lost their life on the streets of our city, Zohran Mamdani said on Monday, adding that each life lost is a tragedy, and we will continue to hold their families in our thoughts.

While temperatures are set to rise this week, they remain below average, with Mamdani telling residents to stay safe, stay indoors... [and] keep looking out for one another.

The mayor added that since 19 January, when a Code Blue emergency was announced - which relaxed intake policies for homeless shelters - about 1,400 placements had been made into shelters.

An additional 64 hotel rooms had been added to the city's shelter capacity, with at least another 150 outreach workers on the streets, said Mamdani.

On 27 January, Mamdani said at least 10 of the people who had died were found outdoors. The circumstances of the other deaths are not known.

We have been working hard to keep New Yorkers safe, and we will continue to do so. Because it is not forecast to be above 32 degrees [Fahrenheit] until tomorrow, and 35 degrees is hardly balmy weather, he said.

The US National Weather Service (NWS) reported temperatures would increase to around 0C for most of the week, following persistent freezing temperatures on Monday, adding that highs are typically around 4C for this time of year.

An Arctic airmass introduced hazardous sub-zero wind chills to the region over the weekend, bringing a risk of hypothermia and frostbite, the forecaster cautioned.

Historic records show that the streak of temperatures below freezing lasted 13 days - one of the longest in over 60 years.

NYC's Emergency Management agency warned that following days of extreme cold may pose serious safety risks across the city, including the risk of falling snow and ice from buildings and refreezing roads.