Hikers, dog owners, and even people in their own backyards are running into rattlesnakes in record numbers this year – and doctors say it’s not just anecdotal.
The California Poison Control System (CPCS) has already logged more than 250 rattlesnake-related calls and bites in 2026, blowing past the roughly 200 calls the agency typically fields across an entire year.
Three of those encounters have been fatal – a toll that’s “highly unusual and deeply concerning,” according to Dr. Rais Vohra, medical director of CPCS’s Fresno/Madera division. California normally sees about one rattlesnake death a year.
The surge isn’t confined to the Golden State, either. Colorado and Arizona have reported an uptick in pediatric and adult envenomations severe enough to require large volumes of antivenom – treatment that can run into the tens of thousands of dollars per patient, since each vial costs thousands and severe bites can require dozens of vials.
The Season Started Early – And It Never Really Slowed Down
Snakebite season in California typically kicks off in April and runs through the summer. This year, calls started climbing in January, February, and March – months before rattlesnakes usually become a real concern.
“We are not sure exactly why this trend is happening,” Vohra said, noting that herpetologists are investigating whether it’s tied to habitat shifts, broader environmental change, or simply an unusually active year.
Cal Poly herpetologist Emily Taylor points to timing rather than population size: rattlesnakes didn’t multiply, they just woke up sooner.
An early-season heat wave pulled them out of winter dormancy weeks ahead of schedule, kicking off what she described as an unusually busy, snake-filled March.
Meet the Snake Behind the Headlines
Most of California’s rattlesnake encounters involve the western rattlesnake group – primarily the Northern Pacific rattlesnake (Crotalus oreganus) in the north and central part of the state, and the Southern Pacific rattlesnake (Crotalus oreganus helleri) in the south.
Both are large, heavy-bodied pit vipers, typically 2-4 feet long, with the telltale triangular head, blotched brown-and-tan camouflage pattern, and segmented rattle at the tail.
Habitat: These snakes favor drier terrain – grasslands, brushland, rocky outcrops, and forest edges – but they steer clear of true desert.
They’re comfortable from sea level up into the foothills and mountains, which means they overlap heavily with California’s most popular hiking trails.
Diet: They’re ambush predators that rely on heat-sensing facial pits to locate warm-blooded prey. Adults eat mostly small mammals – ground squirrels, mice, rats, rabbits – plus birds and bird eggs; juveniles start out eating lizards and insects before graduating to bigger prey.
Danger level: Their venom is primarily hemotoxic, meaning it breaks down tissue and disrupts blood clotting, which is why untreated bites can cause severe swelling, internal bleeding, and tissue damage.
Despite that, rattlesnakes are generally described by wildlife experts as unaggressive: their first instinct is to freeze and rely on camouflage, not strike. Rattling, posturing, and biting are last-resort defenses when a snake feels cornered or threatened.
Where they hide – including near people: Rattlesnakes shelter in rock crevices, hollow logs, dense brush, and abandoned rodent burrows.
Critically, that list also includes spaces humans create: woodpiles, under decks and sheds, crawl spaces beneath houses, overgrown backyard landscaping, and garages left open at ground level.
As suburban development pushes further into foothill and grassland habitat, more of these hiding spots end up a few feet from a back door.
Why the Heat Matters So Much
Rattlesnakes are cold-blooded, so their activity is dictated almost entirely by temperature. In a normal year, they spend winter in underground dens – sometimes communal ones holding dozens of snakes – and only emerge once the ground warms enough in spring.
An early, intense heat wave short-circuits that schedule. Warmer temperatures earlier in the year trigger snakes to leave their dens weeks ahead of the usual timeline, which both starts the biting season early and stretches it out longer on the back end.
During peak summer heat, the snakes also shift their activity toward dawn, dusk, and even after dark, when it’s cooler – meaning the “safe” midday hiking window isn’t necessarily safe at all.
Experts monitoring the trend, including the Biothreats Emergence, Analysis and Communications Network (BEACON), say the same early-warmth pattern driving California’s surge is also fueling increased rattlesnake activity in parts of Colorado.
How to Protect Yourself
Public health officials are urging basic precautions for anyone heading outdoors:
– Stay on cleared trails; avoid tall grass and dense brush.
– Wear boots and long pants.
– Check logs, rocks, and woodpiles visually before sitting or reaching.
– Skip the earbuds outdoors so you can hear a warning rattle (though snakes don’t always rattle before striking).
– Keep dogs leashed – vets report a rise in pet bites, and rattlesnake vaccines are available for dogs.
– If bitten: call 911 immediately, stay as calm and still as possible, remove rings or tight jewelry near the bite, and get to a hospital fast. Do not apply ice or attempt to cut or suction the wound.
The California Poison Control hotline (1-800-222-1222) is available 24/7 for guidance on suspected bites.
Sources:
– ABC7 San Francisco, (“California seeing spike in rattlesnake bites as poison control reports dozens of emergency calls and multiple fatalities” – abc7news
– KTLA, (“California officials report significant increase in rattlesnake bites this year”) – ktla.com
– NewsNation, (“Why California rattlesnake bites are spiking in 2026”) – newsnationnow.com
– Yahoo News/AP, (“Why rattlesnake bites in California are surging”) (yahoo.com)
– AOL/LA Times, (“It’s not your imagination. This is a weird rattlesnake season.”) – aol.com
– Lassen News, (“California sees unusual spike in rattlesnake bites – including three deaths in 2026”) – lassennews.com
– Burke Museum, National Wildlife Foundation, and A-Z Animals species profiles on the Northern Pacific / Western rattlesnake
– California Poison Control System: calpoison.org
