Millions of people across the United States have been issued safety warnings amid concerns over very high temperatures.

TONIGHT: A spotty storm possible through sunset, though chances are low at 20%. Warm and muggy 80s.

NYC faces another excessive heat warning Tuesday, while parts of Long Island and New Jersey are under a heat advisory.

As a heat wave hits multiple U.S. states, some areas are have been placed under extreme heat watches and warnings.

The National Weather Service issued an extreme heat warning for a second day as the heat index surpasses 100. See how hot it ...