Weather Blog

There's a reason it's called "Death Valley"

There's a reason it's called "Death Valley"
Late afternoon on Mesquite Flat Sand Dunes (Photographer: Alan Van Valkenburg)

You know it's toasty when even the hottest place in the nation breaks a sweat.

Temperatures over 100 are quite routine in Death Valley in the summer - heck, even 110+ is not too unusual. But a solid heat wave these past few days have been a scorcher even by their standards.

Between July 15 and 19, the high temperature there has been over 120 degrees each day, with three of the days hitting 125. I'm not sure if the streak is current because there climate page is not yet updated for July 20.

But what was even more interesting to me were some of their overnight lows -- 102 on July 18 and 101 on July 19. That means they went at least 48 hours with a temperature above 100!

Typically they'll drop down into the upper 80s to mid 90s overnight as the clear skies allows that heat to radiate back into space.

Why so hot there? They get a double whammy. Not only are they in the heart of the desert, but at some spots that are over 250 feet below sea level, allowing higher pressures that contribute to heating.

Here is a more detailed explanation, from the Death Valley National Park website:

"The valley is a long, narrow basin 282 feet (below sea level, yet is walled by high, steep mountain ranges. The clear, dry air and sparse plant cover allow sunlight to heat the desert surface. Heat radiates back from the rocks and soil, then becomes trapped in the valley's depths... Heated air rises, yet is trapped by the high valley walls, is cooled and recycled back down to the valley floor. These pockets of descending air are only slightly cooler than the surrounding hot air. As they descend, they are compressed and heated even more by the low elevation air pressure. These moving masses of super heated air blow through the valley creating extreme high temperatures."

Death Valley does hold the Northern Hemispheric high temperature record of 134 degrees on July 10, 1913 at Furnace Creek (gee, wonder where they got that name?). During that period, they had five days at 129 or hotter. Ironically, that year also had their coldest reading of 15 degrees on Jan. 8.

In the summer of 2001, they had 154 days in a row at 100 or hotter, while in 1917, they had 43 straight days of 120 or hotter, so perhaps this current five day streak of 120+ is not all that unusual.