Weather Watch

Watch out for rattlesnakes when SLO County’s weather is warm

The northern Pacific rattlesnake is the most common variety found in San Luis Obispo County.
The northern Pacific rattlesnake is the most common variety found in San Luis Obispo County. East Bay Times

The sun’s radiation was at its greatest for the entire year at the summer solstice — the longest day of the year on June 20.

Our atmosphere is a lot like a large freight train; it takes a lot of energy to get it going. The warmest months in San Luis Obispo County occur July through October.

Paso Robles peaks in July with an average maximum temperature of 93.8 degrees and with a slightly cooler August average high of 93.5 degrees. San Luis Obispo reaches its warmest time of the year in September, with an average high of 77 degrees. Along most of the county’s beaches, October tends to be the warmest month. That’s because the Santa Lucia (northeasterly) winds start to blow, pushing the marine layer out to sea and leaving behind clear skies.

As warmer weather develops in the coastal valleys and along the beaches of the county, more of us head out to hike and enjoy our numerous trails.

On one of these warm October days in 2004, our family went hiking on the Bluff Trail at Montaña de Oro State Park. Sean, who was about a year old at the time, was in a stroller pushed along by my wife, Trish, and I when we heard the unmistakable sound of rattlers in the coastal sage in front of us. Immediately but slowly, we backtracked from the sound of the rattles. I still cringe about the thought of a rattlesnake striking at our young son.

Not only does the warmer weather bring out more people, but it brings out the reptiles as well, increasing the chances of encounters between them and us. Snakes become much less active during the winter months, often hibernating. The majority of snake bites in California occur between the months of April and October.

Thankfully, most of our local snakes are nonvenomous, with the exception of the rattlesnake. The most commonly found rattlesnake in San Luis Obispo County is the northern Pacific rattlesnake (Crotalus oreganus). Rattlesnakes are just about found everywhere in the state, from the beaches to elevations of 10,000 feet or more in the Sierra Nevada.

Generally, rattlesnakes are shy creatures and will gladly retreat if given enough room, but their bites can be extremely dangerous and require immediate medical attention. More than 800 people are bitten each year, resulting in one or two deaths per year in our state, according to the California Poison Control Center. Most snake bites are accidental and occur on hands, ankles and feet while hiking or climbing. Just about a quarter of all rattlesnake bites are “dry,” where no venom is injected.

In the summer edition of the Central Coast State Parks Association “Nature Notes,” Norma Wightman wrote an interesting article about rattlesnake myths. One question often asked: Are baby rattlers more venomous?

She wrote: “At birth, they are miniature adults. Snakes can modulate the amount of venom and inject depending upon the size of the prey. Young rattlers have a neurotoxin type of venom that will block the mobility (heartbeat, diaphragm muscles, etc.) of prey such as lizards that otherwise would escape quickly. As the snake matures and prey becomes larger (small mammals), venom contains more of a digestive or protein-shredding enzyme.”

Rattlesnakes that live in the desert and prey primarily on large lizards have both kinds of toxin.

One myth that happens to be true is that dead rattlesnakes can still bite. They have a heat-sensing structure called a loreal gland between the eye and the nostril. This is the so-called “pit” of the pit viper. This gland helps them locate warm-blooded prey in darkness. When a rattlesnake is killed, this gland does not immediately stop working. If a warm mass, such as your foot or hand, is placed in front of this gland on a freshly killed rattlesnake, it will cause the snake’s body to strike.

Overall, rattlesnakes are in an important part of the ecosystem as they eat rodents and are eaten by other predators. It’s possible to live safely around rattlers by taking precautions. The California Department of Fish and Wildlife recommends:

▪  Never go barefoot or wear sandals when walking through wild areas. Wear hiking boots.

▪  When hiking, stick to well-used trails and wear over-the-ankle boots and loose-fitting long pants. Avoid tall grass, weeds and heavy underbrush where snakes may hide during the day.

▪  Do not step or put your hands where you cannot see and avoid wandering around in the dark. Step on logs and rocks, never over them, and be especially careful when climbing on rocks or gathering firewood. Check out stumps or logs before sitting down, and shake out sleeping bags before use.

▪  Never hike alone. Always have someone with you who can assist in an emergency.

▪  Teach children to respect snakes and to leave them alone. Children are naturally curious and will pick up snakes.

Siren test coming up

On Saturday, Aug. 27, the San Luis Obispo County Early Warning system Sirens and the Reverse 911 System will be tested. These systems may be used for any local emergency.

The Early Warning System sirens will sound at noon and again at 12:30 p.m., and they will last for three to five minutes. During these tests, no action is required on the part of the public.

If you hear sirens at any other time, tune to a local radio or television station for emergency announcements. This message is from the county Office of Emergency Services and PG&E.

John Lindsey is PG&E’s Diablo Canyon nuclear power plant marine meteorologist and a media relations representative. Email him at or follow him on Twitter @PGE_John for weather and other useful information.