Well, it doesn't get very cold where a person is, but there are plenty of microhabitats that salamanders and newts can utilize that are significantly cooler than the majority of their surroundings. In burrows underground, the edges of cool spring fed streams, the bottoms of lakes, etc are all significantly cooler than standard air temps in the sun. Newts and salamanders live in these cooler places around and underneath the warmer ones.
Their are some tropical species of salamanders. Many of them are high altitude animals, but I would imagine some of the salamanders of the Bolitoglossa family would be a little more heat tolerant. There are not many in captivity and those imported from South America do no usually last long.
And as Ian said, I've heard the same thing about Cynops ensicauda and their resistance to higher temperatures.