At a glance

The largest recent blaze in the Mother Lode was earlier this month:

• The Pacheco Fire broke out July 12 and burned more than 340 acres near Lanford Pacheco Road and Milton Road in Calaveras County.

Blazes so far this week include:

•The Reed Fire broke out Sunday and burned 3 acres near the 2100 block of Pool Station Road and the 100 block of George Reed Drive in Calaveras County.

•The Lambert Fire broke out Sunday and burned a travel trailer and one-third of an acre near Christian Heights Assembly of God Church and Joshua Way in Sonora.

•The Brookside Fire broke out Monday and burned a home, vehicles and trees near the 16000 block of West Brookside and the 16000 block of Hillside Drive in Cedar Ridge.

•The Center Fire broke out Monday afternoon near the 8000 block of Del Orto and 9000 block of Center Street in Mokelumne Hill.

In the past two months TCU personnel have responded to 70 wildland fires, 25 debris fires, 10 residential fires, 9 vehicle fires, 62 false alarms and 3 smoke checks. The June-July totals include 37 wildland fires so far this month.

SOURCE: Cal Fire Tuolumne Calaveras Unit

The current dry heat wave this week is expected to bring highs above 100 degrees today through Thursday in Sonora and other towns on the Highway 49 corridor, increasing fire dangers in the Mother Lode and Central Sierra forests.

Forecasters say the outlook for Sonora the rest of this week calls for “seasonably hot temperatures” up to 103 today, 103 Wednesday, 101 Thursday, 98 Friday and 95 Saturday.

In spite of dry heat and increasing tree mortality in overcrowded mountain forests, Tuolumne and Calaveras counties so far this year have been spared eruptions of megablazes on par with the 2015 Butte Fire and the 2013 Rim Fire.

Before noon Monday, fire destroyed a home, an outbuilding and two vehicles on Hillside Drive in a Cedar Ridge neighborhood, above Phoenix Lake. Elsewhere in the state, destructive fires were burning out of control Monday in Monterey and Los Angeles counties.

Nature dictates

Whims of nature, including lack of sustained high winds, have helped firefighters keep local fires from growing into catastrophic infernos in the Mother Lode so far this year.

The Soberanes Fire near Big Sur and the Sand Fire near Santa Clarita had forced thousands of evacuations as of Monday afternoon. An unidentified burned body was found Saturday night in a car in a Santa Clarita driveway, according to the Los Angeles County Sheriff’s Department.

Chief Josh White, of Cal Fire’s Tuolumne-Calaveras Unit, said Monday firefighters working the Soberanes and Sand fires are facing major challenges, including limited access and steep terrain.

“We have experienced that locally as well, with the Appaloosa, Campo and Pacheco incidents,” White said. “Fortunately we were able to contain these fires, before they went to major incidents, with strong initial attack forces.”

Assistance from local fire departments, other Cal Fire units and the Forest Service have helped TCU fire crews keep local blazes from growing to disastrous proportions so far this fire season, White said. But all the dangers are still there and threats are heightened when dry heat clamps down.

“With these high temperatures and low humidities, the fuels are continuing to dry out,” White said. “Even the live fuel moistures are starting to hit critical levels and will only continue to get worse for the next few months. It is imperative that our communities strive to be safe and cautious with all possible ignition sources.”

Common sense

Dean Kelaita, public health officer for Calaveras County, issued a heat advisory Monday morning. Kelaita is based in San Andreas, where forecasts call for highs of 105 today, 106 Wednesday, 105 Thursday, 105 Friday and 101 Saturday.

“Taking action now can prevent the possibility of heat-related illness,” Kelaita said. “Some health conditions such as obesity, fever, dehydration, heart disease, poor circulation, sunburn and drug/alcohol use can make it harder for the body to say cool in hot weather.”

Kelaita urged people to use common sense during the warm spell. Simple steps to avoid being overcome by heat include drinking plenty of water and taking extra with you if you venture outside on foot or in a vehicle. Caffeinated drinks and alcohol can increase the likelihood of dehydration.

Other obvious things people should do in triple-digit heat include providing plenty of water for pets, staying cool by staying indoors, taking cool showers and baths, and seeking out air conditioning when possible.

“If you do not have air conditioning, go to a place that is air conditioned,” Kelaita said.

Public libraries, big box stores and movie theaters are among locations with free air conditioning in Tuolumne and Calaveras counties.

People who go outside should wear lightweight, loose-fitting clothing, sunscreen and wide-brimmed hats, and plan to rest often in shady areas. Never leave children or pets in parked cars.

“Don’t overestimate what you can do during a heat wave,” Kelaita said. “Assume it should be less than your normal level of activity.”

Why so hot?

Newcomers to the Mother Lode often wonder why it’s so hot in the foothills of the highest mountain range in 48 states.

Scientists say climates of the Sierra Nevada vary from hot desert, similar to the Sahara, at its eastern base to arctic-alpine on the highest peaks, with most of the range subject to Mediterranean or microthermal, low-temperature climates.

Mediterranean climates dominate the Sierra below about 6,000 feet elevation, especially on west slopes that include the Mother Lode, where climates are characterized by warm to hot, dry summers and cool to cold, wet winters.

Sonora, San Andreas and other Central Sierra towns are situated in “Hot Summer Mediterranean” climates with hot, dry summers. The hot summer climate zone is from around 3,000 feet elevation down to the valley floors. Vegetation here is often described as the chaparral zone of the Sierra foothills.

Chaparral species rely on fire to regenerate and they are among the world’s most fire-friendly ecosystems.

Very dry, hot summers have profound effects on foothill plants and animals, according to Climate and Weather of Central California’s Sierra Nevada Foothills at

Hot, droughty summers are the most extreme feature of the foothills climate, so plants and animals typically show adaptations to summer drought. Many plants thrive during rainy months, then pass through summers in seed stage. During dry seasons the foothill landscape is straw colored, except for perennial plants with very deep roots.

Jim Conrad wrote in a Naturalist Newsletter for California’s Sierra Nevada Foothills in October 2004 that vegetation odors in the Sierra foothills reminded him of Corsica, a mountainous Mediterranean island between France and Italy.

“One feature of the Mediterranean Biome and its five subtypes is that the vegetation is typically aromatic because the plants produce many fragrant oils,” Conrad wrote. “Often ‘fragrant’ means ‘smells like strong medicine.’ These oils, however they smell, typically taste bitter, and that keeps grazing animals from eating the plants. Such oil-producing plants also burn like crazy, so Mediterranean vegetation is especially vulnerable to wildfire.”

Brace yourself

This week’s heat episode is expected to bring triple-digit temperatures, increased fire weather concerns and moderate risks of heat-related illness for vulnerable groups, especially the very young and elderly, according to National Weather Service staff in Sacramento.

Fire weather concerns are especially heightened at higher altitudes that include significant portions of the estimated 66 million dead trees in Sierra Nevada forests. Low humidities with poor overnight recovery are expected to increase fire dangers in higher terrain.

For anyone who has to head to lower altitudes, valley temperatures could reach to 110 degrees and hotter. Near-record high temperatures are possible Wednesday and Thursday.

Mother Lode fire crews will be on alert or assigned to incidents through this week.

“Unfortunately, we continue to see homes damaged and destroyed in these fires,” White said. “It is imperative for homeowners to do everything they can, safely, to remove the flammable vegetation from around their homes. Homeowners should also be ready to evacuate at a moment’s notice. When the Sheriff calls for an evacuation, leave.”

The tree mortality epidemic in Tuolumne and Calaveras counties is a top concern for everyone in the Mother Lode, White said.

“The threat for a fire to spread faster, burn hotter and allow for spot fires even further away from the head of a fire,” White said, “is a critical threat.”