So if a user from Minneapolis travels to Kansas City, Mo., that person would get local warnings for Kansas City, not their home city. That feature sets the system apart from weather apps that deliver information based on users' ZIP code but don't automatically update their locations when users travel.

Greg Carbin, the warning coordination meteorologist at the national Storm Prediction Center in Norman, Okla, said in a typical year most smartphone users will probably receive relatively few weather alerts.

"Even in those areas of the country where there's a lot of severe weather, the frequency with which you would be alerted is pretty low," Carbin said.