California has 7 venomous land snakes named by official sources: Western Rattlesnake, Sidewinder, Mohave Rattlesnake, Speckled Rattlesnake, Western Diamond-backed Rattlesnake, Red Diamond Rattlesnake and Panamint Rattlesnake. Each one is labelled venomous by University of California Statewide IPM Program and US Centers for Disease Control and Prevention. The yellow-bellied seasnake, a venomous sea snake, is also named.
The 8 venomous snakes of California
Recognize them from a distance; a photo cannot confirm that a snake is safe. Identifying animals safely.
Up to 50 inches excluding the rattle (Arizona). Grand Canyon-Parashant National Monument says it averages 2 to 4 feet. Texas calls it smaller and more slender than the western diamondback.
How to recognize it
Rattle at the end of the tail
Broad triangular head on a slender neck; vertical pupils
Thin light stripe from the back corner of the eye running past the corner of the mouth
Where in California
Are found in the desert and foothills of southeastern California. CWHR Program
JFMAMJJASOND
83 records by month.What the sources say
Venom: “The rattlesnake is California’s only native venomous snake.” (University of California Statewide IPM Program)
Usually about 3.5 to 4.5 feet; Texas says it can reach seven feet. Arizona's maximum is 66 inches excluding the rattle; Saguaro National Park gives a range of 30 to 90 inches.
How to recognize it
Rattle at the end of the tail
Broad triangular head on a slender neck; vertical pupils
Thin light stripe from behind the eye down to the upper lip
Where in California
Are rare in California but can occur in desert areas in the far southeastern part of the state. CWHR Program
What the sources say
Venom: “The rattlesnake is California’s only native venomous snake.” (University of California Statewide IPM Program)
Varies by area and subspecies: up to 63 in. excluding rattle (Arizona); largest in the Northwest 59 in., most Washington adults around 2 ft; 18 to 36 in. average (Oregon); C. o. concolor rarely over 26 in. (Colorado).
How to recognize it
Rattle on the tail; broad triangular head; facial pits
Vertical pupils and heat-sensing pits near the nostrils
Strongly keeled scales
Where in California
Western rattlesnakes (PDF) (C. oreganus) are the most widespread rattler in California. It is found statewide from sea level up to 7,000 feet. CWHR Program
JFMAMJJASOND
2,118 records by month.What the sources say
Venom: “The rattlesnake is California’s only native venomous snake.” (University of California Statewide IPM Program)
“All 52 known species of sea snakes are venomous, and human deaths from bites have been reported. Sea snake bites are often painless or cause minimal pain but can be very dangerous.” US Centers for Disease Control and Prevention
What the sources say
Venom: “The yellow-bellied sea snake, Pelamis platurus, has also been found along the eastern Pacific Coast of Central and South America. All 52 known species of sea snakes are venomous, and human deaths from bites have been reported.” (US Centers for Disease Control and Prevention)
For 27 other snakes on California's list, no official source we use states whether it is venomous: Aquatic Gartersnake, Baja California Coachwhip, Baja California Ratsnake, Brahminy Blindsnake, California Lyresnake, Checkered Gartersnake, Coast Nightsnake and Common Gartersnake and others. That does not make them harmless. Leave every snake alone.
WDFW: racers have large eyes, large back scales and a tail that tapers to a point; rubber boas have small eyes, tiny scales and a blunt tail. Racers are fast and will strike and bite if cornered or handled; rubber boas are slow and non-aggressive. Yellowstone adds that racers have round pupils.
Gopher snake (gophersnake) or Glossy snake?
Photo: National Park Service from USA · Public domain · Wikimedia Commons
TWRA: the racer lacks the coachwhip's reddish tint along the sides of the tail; an all-black coachwhip is distinctly lighter or reddish toward the rear. Oklahoma: the coachwhip is much larger.
Western Rattlesnake or Gopher snake (gophersnake)?
WDFW (Washington): no rattle and no facial pits, oval pupils, smaller square spots, a narrow eye stripe and less keeled scales. It can coil, strike, hiss loudly and vibrate its tail like a rattlesnake, so behavior alone does not tell them apart.
Photos show typical adults; individuals vary. Never get close to compare.
When venomous snakes are active in California
Records of snakes in California peak in March to June. They show when people record snakes, not how many there are (about month bars).
JanFebMarAprMayJunJulAugSepOctNovDec
10,815 records of snakes in California by month (GBIF, CC0 and CC BY records).
Rattlesnakes: most active at dawn, dusk and night in spring and summer; inactive/brumating in fall and winter; most bites April-October California Department of Fish and Wildlife
Wildlife conflicts: CDFW Wildlife Incident Reporting (WIR) system https://apps.wildlife.ca.gov/wir, emergencies 9-1-1. Invasive animal sightings: CDFW Invasive Species Program (866) 440-9530 or [email protected]; invasive insects/spiders/terrestrial invertebrates: California Department of Food and Agriculture 1-800-491-1899. California Department of Fish and Wildlife
“Of the 14 snakes found in the Santa Monica Mountains, only one, the southern Pacific rattlesnake (Crotalus viridis), is venomous. … Other less common species include the blind snake (Leptotyphlops humilis)”
“Of the 14 snakes found in the Santa Monica Mountains, only one, the southern Pacific rattlesnake (Crotalus viridis), is venomous. … blackhead snake (Tantilla planiceps)”
“Of the 14 snakes found in the Santa Monica Mountains, only one, the southern Pacific rattlesnake (Crotalus viridis), is venomous. … red coachwhip (Masticophis flagellum)”
“Of the 14 snakes found in the Santa Monica Mountains, only one, the southern Pacific rattlesnake (Crotalus viridis), is venomous. … California striped racer (Masticophis lateralis)”
“Of the 14 snakes found in the Santa Monica Mountains, only one, the southern Pacific rattlesnake (Crotalus viridis), is venomous. … coast patch-nosed snake (Salvadora hexalepis)”
“Of the 14 snakes found in the Santa Monica Mountains, only one, the southern Pacific rattlesnake (Crotalus viridis), is venomous. … two-striped garter snake (Thamnophis hammondii)”
“Non-venomous snake species exist, too, in Yosemite such as kingsnakes and yellow-bellied racers.”
Rattlesnake. California Department of Fish and Wildlife. undated page; checked November 3, 2026.Quoted passages (7)
“Some snakes can mimic the appearance of a rattlesnake, such as the gopher snake (Pituophis catenifer), but are non-venomous and lack a rattle.”
“For more information, call the California Poison Control System at (800) 222-1222. In the event of an emergency situation, call 9-1-1 and seek medical attention immediately.”
“DO NOT try to touch or handle a snake, dead or alive. Dead rattlers may still inject venom shortly after death.”
“A startled rattlesnake may NOT rattle before striking defensively.”
“In Spring and Summer - Most active at dawn, dusk, and night to avoid overheating. In Fall and Winter - Inactive, and some may go into brumation (a state of dormancy with periods of activity), for several months in rock crevices, rodent burrows, or thick vegetation. … Most bites occur between April and October when snakes and humans are most active outdoors.”
“Rattlesnake courtship and mating occurs once temperatures heat up with the warmer weather (March to May). … Females often nest in old rodent burrows and rock crevices, and give birth to 1 to 25 live young in the Fall.”
“There are seven species of rattlesnake in California:”
“Northern watersnakes are not venomous, but when threatened will strike repeatedly and emit a foul-smelling musk mixed with feces.”
“All subspecies have black, dark brown, or reddish crossbands on the front section of the body that break up into rows of blotches from the middle to the end of the body.”
“Their bellies can be white, yellow, or orange, and commonly have dark half-mooned shaped spots.”
“The yellow-bellied sea snake, Pelamis platurus, has also been found along the eastern Pacific Coast of Central and South America. All 52 known species of sea snakes are venomous, and human deaths from bites have been reported.”
“All 52 known species of sea snakes are venomous, and human deaths from bites have been reported. Sea snake bites are often painless or cause minimal pain but can be very dangerous.”
Pest Notes: Rattlesnakes. University of California Statewide IPM Program (UC ANR, Cooperative Extension). 2014-12; checked November 3, 2026.Quoted passages (2)
“The rattlesnake is California’s only native venomous snake.”
“Rattlesnakes have a rattle in addition to a distinctive triangular head whereas harmless gopher snakes do not have a rattle.”
Report an Invasive Species Sighting. California Department of Fish and Wildlife (Invasive Species Program). undated page; checked November 3, 2026.Quoted passages (1)
“To report a sighting of a known, or suspected invasive species of an animal (mammal, bird, reptile, amphibian, fish, aquatic invertebrate) or marine plant, complete and submit the Suspect Invasive Species Sighting Report form below or contact us at (866) 440-9530. / For a known invasive plant, terrestrial invertebrate (worm, beetle, spider, bug, bee, fly, ant, snail, etc.) or plant/tree disease, or one that you suspect may be new to your area of California, contact the California Department of Food and Agriculture at 1-800-491-1899. / [ca-cdfw-hwc] Wildlife Incident Reporting (WIR) System For Emergencies, call 9-1-1”
.jpg){kind=link}
.jpg){kind=link}
.jpg){kind=link}
.jpg){kind=link}
.jpg){kind=link}