By the year 2100, the city is likely to be hotter and rainier, with climbing sea levels putting coastal regions more at risk of floods and storms like deadly Hurricane Sandy, according to a report from the New York City Panel on Climate Change released today.

“Hurricane Sandy certainly highlighted a lot of our vulnerabilities to these kinds of risks, certainly around sea level rise and coastal storms,” Director of the Mayor’s Office of Recovery and Resiliency Daniel Zarrilli said at an afternoon briefing at City Hall.

The report includes projections on how sea levels, precipitation and temperature will change by 2050, 2080, and 2100 in New York City.

“They show significant risks of climate change,” Cynthia Rosenzweig, a senior research scientist and co-chair of the panel, said. The worst-case scenario, she said, is that sea levels could rise up to six feet by 2100.

Other projections in the report include warning that temperatures may increase by up to 5.7 degrees by 2050s, and by up to 8.8 degrees by the 2080s, compared to the 1980s. Precipitation is projected to get worse, too—increasing by up to 11 percent by the 2050s and 13 percent by the 2080s, also compared to the 1980s. And the frequency of heat waves is likely to jump from two per year today to six per year by 2080.

“The projections that we’re hearing about assume that we don’t act in many ways, and I think the good news here is we as a city are continuing to act,” Mr. Zarrilli said.

Mr. Zarrilli pointed to the city’s efforts to reduce carbon emissions, which scientists have linked to the warming of the planet, with goals of cutting down the city’s emissions by 80 percent by 2050. But even as they hope to forestall some the more dire projections, the city is also preparing to face them. New York is already using the 2050 projections in its planning for future buildings, including affordable housing Mayor Bill de Blasio hopes to erect in the Stapleton neighborhood of Staten Island, in a flood zone.

The report urges the city to identify the neighborhoods most vulnerable to future storms and other climate impacts and build resiliency there, to look at community-based adaptation to make those neighborhoods safer, and to protect its infrastructure.

As sea levels rise, more and more homes will be at risk for coastal flooding, the report notes—with more homeowners already being categorized as flood-prone in new flood insurance maps set to be adopted by the city. The city’s Build it Back program will elevate some participating and qualifying homes hit by Sandy, protecting them from future storm surges. But some have griped the city’s approach to making neighborhoods safer after Sandy has been piecemeal, without visions for changing entire swaths of vulnerable older homes on low-lying land.

Mr. Zarrilli said the city is also looking how it can use the land use process to encourage more resilient neighborhood planning going forward, and he noted new construction held up much better to Sandy than older neighborhoods. When it comes to existing, older homes, he said the city will turn to shoreline and coastal protections like dunes and even levees—but won’t look to cut off communities from shoreline access the city has spent the last decade opening up.

“We need to continue to re-engage and exist on the waterfront in a slightly different way given these risks,” he said.

Among the first major coastal protections underway is a storm barrier for the Lower East Side.

The goal for barriers and levees planned around the city, Mr. Zarrilli said, will be “making sure that those don’t necessarily feel like flood protection, that they not necessarily wall us off from the waterfront we’ve spent a long time re-engaging with.”

The New York City Panel on Climate Change, made up of scientists independent from city government, was launched by former Mayor Michael Bloomberg and issued its first report in 2010.