(sirens blaring) - [Narrator] When it comes to our changing weather, heat is one of the biggest killers.

- I don't think people immediately think heat waves, they think hurricanes, they think wildfires, but heat is the silent killer.

- [Narrator] Since the 1930s, average temperatures in Atlanta have risen about three degrees Fahrenheit but the average isn't what matters.

- When you shift that a couple of degrees, it puts you in a whole different climate zone.

It's a bell curve.

We're looking at a distribution of temperatures, a couple of degrees, a slight change in that average shifts you into an entirely new area, where the hot's get put in extreme heat, that's when we have to rearrange our lifestyles.

- [Narrator] Extreme heat overwhelms human bodies, muscles slow, heartbeats weaken, blood pressures plunge, kidneys shut down.

Days over 90 degrees have been linked to over 1,000 deaths a year In the US.

(dramatic music) - Most cities only utilize a single thermometer to measure the weather.

That is your basic airport weather station, and that is a rather ludicrous proposition.

We need to be measuring temperature and humidity extensively across cities.

(upbeat music)