The extreme daytime temperatures of an urban heat-wave may be hard to ignore, but really, scientists say, it's the nights that kill you.
The tragedy of Paris in 2003 - the deaths of 5,000 vulnerable people in the first two weeks of August - spawned a raft of new studies on the subject of death-by-weather, a researchers presented their findings this week at the annual meeting of the American Geophysical Union in San Francisco.
Half of us live in cities, and just 20 years from now 80 percent of us are expected to be urban dwellers. Cities are the lifeblood of the modern economic times, no doubt about it, but they are also the boiler rooms. And the rising frequency of lethal heat waves across the globe is prompting a more detailed look at the "urban heat island" effect.
Using satellite data, Ping Zhang and colleagues at NASA's Goddard Space Flight Center compared the different heat-generating signatures of thousands of cities around the planet, and their findings confirm that the strongest heat islands are the larger, most densely developed cities.