Autumn Makes a Sultry Entrance

California’s heat wave came late and is staying late

Sunset on San Pablo Bay. Coastal areas saw a balmy end to September, accompanied by air quality alerts.

The Great American Heat Wave of 2012 arrived later in California than in many parts of the country — and it’s in no hurry to leave.

Having nudged the upper 90s on Sunday, Sacramento closed out the month of September with a record 26 days of 90-plus highs, surpassing the 1974 record of 24 days. The trend is forecast to continue into the first several days of October, with a chance of hitting 100 for the first time since mid-August. Farther north, Sacramento Valley towns like Redding and Red Bluff are suffering similar bake-offs. Continue reading

Study: Western Streams Resist Influence of a Warming Climate

Streams show varied response

Hot Creek, near Mammoth Lakes, was one of 20 streams in the Western U.S. examined in a study by Oregon State researchers who found no clear relationship between increasing air temperatures and stream temperatures.

Rising sea levels, melting glaciers, intensifying storm events – evidence is mounting that the effects of a warming planet will be far-reaching and potentially catastrophic. But one natural system may be more resilient than others when it comes to global warming: mountain streams.

Researchers from Oregon State University report in the journal Geophysical Research Letters that small streams in the western United States have not heated up in response to the region’s warming air temperatures.

Water temperature is a critical variable for aquatic ecosystems. Some fish, for example, time egg-laying to minute changes in water temperatures; in other species, stream temperatures are a key factor in determining the sex of juvenile fish. Continue reading

This Winter Looking Like Fourth Warmest for Lower 48

Could be second-driest winter on record for California, Pacific Northwest

Rain comes late to Northern California: A March storm front hovers over San Pablo Bay, north of San Francisco.

Last week’s State of the Climate report issued by the National Oceanic and Atmospheric Administration found that this winter is stacking up as the warmest since 2000 and the fourth warmest on record in the contiguous United States.

According to NOAA, 47 of 48 states experienced above-average temperatures in the period between December and February, with the greatest increases seen in the Northeast and Midwest.

Only New Mexico saw below-average temperatures. Continue reading

The Long, Hot Summer: Longer & Hotter

Stanford study predicts the point of no return for hotter summers

By Katrina Schwartz

Just as many Californians are puzzling over winter-like weather in June, climate scientists are saying hotter days are ahead for most of the West. According to a new Stanford study (available soon at this link), we may be in for permanently hotter summers sooner than expected. Of course, for climatologists, “sooner” is a relative term.

Photo: Craig Miller

Plenty of climate scientists have studied the relationship between climate change and extreme temperature shifts, but until now no one has tried to pinpoint a moment when summer temperatures will permanently shift into a new “heat regime”, in which the coolest summer temperatures will be hotter than the hottest summer temperatures of the previous regime. Findings by the Stanford team suggest that the shift will likely happen sooner and be more widespread than expected. Continue reading

Despite a Cool Summer, LA is Getting Hotter

It was looking like a cool summer in Los Angeles until a couple of weeks ago.  Temperatures in downtown LA topped 90 degrees Fahrenheit only once this summer until September 25th.  Since then, according to the National Weather Service’s Climatological Report, the city has seen 4 days above 90, including today. Which is what a group of university and NASA scientists say Southern Californians had better get used to.  

The scientists analyzed 100 years of temperature data collected in downtown Los Angeles  and found that between 1906 and 2006 the average number of extreme heat days – those over 90 degrees – increased from 2 per year to more than 25 per year.  In that time, the average maximum daytime temperature for the city climbed 5 degrees.  Heat waves have also increased, from 2-day events to sweltering stretches that last for 1-2 weeks. The scientists predict that in the coming decades, 10-14 day heat waves will be the norm. 

The bottom line? Even though this summer was a cool one, Southern California is going to get warmer, for longer periods of time. “Our snow pack will be less, our fire seasons will be longer, and unhealthy air alerts will be a summer staple” said study co-author Bill Patzert, a NASA climatologist and oceanographer.

The scientists assert that the main cause of this increase in temperature and heat days in Los Angeles is due the “urban heat island effect,” which makes urban areas 2-10 degrees Fahrenheit warmer than the surrounding rural areas.

Check out a historical temperature chart for downtown Los Angeles and a full report on the study here.