Weather Watch

Human activity sparks most wildfires

Cal Fire and PG&E are partnering in a public information campaign about reducing wildfire risk.
Cal Fire and PG&E are partnering in a public information campaign about reducing wildfire risk.

The last three rain seasons have been the second driest on record at Cal Poly (home of climatology for San Luis Obispo), with a total of 39.6 inches of rain.

The driest three-year timeframe occurred from 1958 through 1960, during which only 38.8 inches of rain fell. No other three-year period is near these two.

Unlike 1958-1960, the current three-year drought is warmer. In fact, 2014 is on pace to be the warmest year on record in the county. This extended drought combined with record-breaking heat and unusually strong spring Santa Lucia (offshore) winds has left vegetation in San Luis Obispo County with extraordinarily low moisture content. That, in turn, has increased the threat of wildfire.

“We are seeing fuel moisture readings in brush at or near record lows in San Luis Obispo County,” said Steve Reeder, deputy chief for Cal Fire in San Luis Obispo.

As any firefighter will tell you, three ingredients are needed to have a fire — oxygen, heat, and fuel — “the fire triangle.” A heat source such as a spark from a trailer chain hitting the highway can cause a fire to ignite, but the heat also preheats the fuel in the fire’s path, allowing it to spread.

This year’s heat has helped to dramatically lower the moisture content of vegetation, allowing it to burn easier and hotter.

Along with the warm temperatures, this year’s unusually strong winds not only helped to dry vegetation through evaporation; but could also provide plenty of oxygen for combustion if the fire was to break out. Overall, warmer temperatures, stronger winds and drought have fed into an awful feedback loop.

The number of fires this year bears this out. On average over the last five years, there were 1,828 fires by the end of June. This year, there were already 2,715 fires, according to Cal Fire.

“This is first time in my career that we have a fire season that did not end and just kept going through the winter and now into the summer,” said Robert Lewin, fire chief for Cal Fire in San Luis Obispo.

These dire conditions will greatly exacerbate the challenge that Cal Fire and other fire departments already face to carry out their mission of the protection of life, property and natural resources.

According to Cal Fire, nearly 90 percent of all wildfires in California are caused by people, often when they are engaged in routine activities. Simple tasks such as mowing the lawn, using a weed eater or chain saw can spark a wildland fire.

In other words, if you can prevent the initial ignition, you can prevent the vast majority of wildfires.

Earlier this week, PG&E and Cal Fire announced a partnership to help stop wildfires before they start in California. Cal Fire’s “One Less Spark, One Less Wildfire” public safety campaign is a multi-agency effort to minimize the frequency, size and cost of wildfires started by human activity.

PG&E is joining the campaign by reminding its 22,000 employees and encouraging the 15 million Californians it serves to practice safe outdoor equipment use, and to properly use and maintain all vehicles.

“At PG&E, there’s nothing more important to us than public safety,” said Barry Anderson, PG&E’s vice president of emergency preparedness and response. “Wildfires are a huge risk in our service area of Northern and Central California, and PG&E is serious about working with Cal Fire and other state and local agencies to do our part to reduce that risk—including helping educate our customers about fire safety, operating our own equipment responsibly, and being prepared to respond.”

“It is critical that every Californian do their part and take precautions outdoors to prevent sparking a wildfire,” said Chief Ken Pimlott, Cal Fire director.

To help prepare for this fire season, please visit: