Hot L.A. Nights Caused By Urban Heat Island Effect

Climatologists blame the urban 'heat island' effect for a rise in Southern California's average evening temperatures, which have hit record highs in recent days.

1 minute read

July 26, 2006, 1:00 PM PDT

By Irvin Dawid


The recent heat wave has L.A. residents without air conditioning resorting to sleeping in backyards, or renting motel rooms. Energy demand is continuing to strain the region's power grid into the night, because unlike during past heat waves, evening temperatures are remaining high. And the high night temperatures only make the next day that much hotter.

"Climatologists say global warming gets some of the blame. But the prime villain, they say, is the ever-increasing urbanization of the region. The rapid development of Southern California over the last 50 years has created structures and landscapes that retain heat better than dry desert chaparral."

"The extreme makeover Southern California got is impacting nighttime temperatures," said William Patzert, a meteorologist for the Jet Propulsion Laboratory.

"Everybody wants to know why it's not cooling off at night. This is an urban land use 'heat island' effect."

"The numbers tell the tale: Between 1901 and 2000, the average daytime temperature in Southern California has gone up by three degrees, Patzert said. But nighttime averages have risen by seven degrees."

Thanks to Patricia Matejcek

Tuesday, July 25, 2006 in The Los Angeles Times

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Cover CM Credits, Earn Certificates, Push Your Career Forward

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

June 25, 2025 - Diana Ionescu

Map of Western U.S. indicating public lands that would be for sale under a Senate plan in yellow and green.

Map: Where Senate Republicans Want to Sell Your Public Lands

For public land advocates, the Senate Republicans’ proposal to sell millions of acres of public land in the West is “the biggest fight of their careers.”

June 19, 2025 - Outdoor Life

Person wearing mask walking through temporary outdoor dining setup lined with bistro lights at dusk in New York City.

Restaurant Patios Were a Pandemic Win — Why Were They so Hard to Keep?

Social distancing requirements and changes in travel patterns prompted cities to pilot new uses for street and sidewalk space. Then it got complicated.

June 19, 2025 - Diana Ionescu

Green public transit bus at stop in Silver Spring, Maryland.

DC Area County Eliminates Bus Fares

Montgomery County joins a growing trend of making transit free.

5 seconds ago - The Washington Post

Close-up of full beer glass with purple train-themed design sitting on bar between two frosty tall cans.

Platform Pilsner: Vancouver Transit Agency Releases... a Beer?

TransLink will receive a portion of every sale of the four-pack.

June 30 - Cities Today

Vintage red Toronto streetcar passing in front of Rogers Arena in Toronto, Canada.

Toronto Weighs Cheaper Transit, Parking Hikes for Major Events

Special event rates would take effect during large festivals, sports games and concerts to ‘discourage driving, manage congestion and free up space for transit.”

June 30 - blogTO

Urban Design for Planners 1: Software Tools

This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.

Planning for Universal Design

Learn the tools for implementing Universal Design in planning regulations.