Cool Summer, Warm Future: Extreme Heat Days Increase For Southern California

Summer 2008 in Southern California goes down in the books as cooler than normal. The thermometer in downtown Los Angeles topped 90 degrees Fahrenheit (32.2 degrees Celsius) just once in July, August and the first two-thirds of September. But don't expect this summer's respite from the usual blistering heat to continue in the years to come, cautions a group of NASA and university scientists: The long-term forecast calls for increased numbers of scorching days and longer, more frequent heat waves.

The team forecasts that in coming decades, we can expect 10- to 14-day heat waves to become the norm. And because these will be hotter heat waves, they will be more threatening to public health.