Washington has 1 venomous snake named by official sources: Western rattlesnake. It is labelled venomous by Washington Department of Fish and Wildlife. It also lists 1 snake as mildly venomous or not dangerous to people; it is shown separately below.
The venomous snake of Washington
Recognize them from a distance; a photo cannot confirm that a snake is safe. Identifying animals safely.
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
Venom: “Caution: This is a venomous and potentially dangerous snake.” (Washington Department of Fish and Wildlife)
Range: Western rattlesnakes occur east of the Cascade Mountains in the East Cascades, Columbia Basin, Okanogan, and Blue Mountain ecoregions. The furthest west they have been documented is in the Columbia Gorge approximately 1 mile west of Dog Mountain in Skamania County.
Habitat: In Washington, western rattlesnakes primarily occur in shrubsteppe habitats but are also found in Oregon white oak, ponderosa pine and other open forest types. (Washington Natural Heritage Program, Washington Department of Fish and Wildlife, BLM and U.S. Forest Service)
For 4 other snakes on Washington's list, no official source we use states whether it is venomous: Common sharp-tailed snake, Northern rubber boa, Ring-necked snake and Western racer. That does not make them harmless. Leave every snake alone.
Mildly venomous snakes
Washington Department of Fish and Wildlife lists this snake as mildly venomous or not dangerous to people. Each card quotes what the source says about its venom. Like any snake, leave them alone.
Venom: “The nightsnake’s fangs are in the back of the mouth (‘rear-fanged’) and the venom is ‘chewed’ into the wound of their prey.” (Washington Department of Fish and Wildlife)
Habitat: Most nightsnake occurrences in Washington are from arid areas that support shrubsteppe vegetation, but occurrences in the Leavenworth area are in ponderosa pine forests. (Washington Natural Heritage Program, Washington Department of Fish and Wildlife, BLM and U.S. Forest Service)
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.
Rubber Boa or Racer (Western Yellow-bellied Racer)?
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.
Photos show typical adults; individuals vary. Never get close to compare.
When venomous snakes are active in Washington
Records of snakes in Washington peak in April to July. They show when people record snakes, not how many there are (about month bars).
JanFebMarAprMayJunJulAugSepOctNovDec
950 records of snakes in Washington by month (GBIF, CC0 and CC BY records).
Dangerous wildlife: emergency 911; non-emergency 877-933-9847 or the WDFW online report. Invasive species: Washington Invasive Species Council web form or WA Invasives app; aquatic invasive species hotline 1-888-WDFW-AIS, [email protected]. Washington Department of Fish and Wildlife
“Caution: This is a venomous and potentially dangerous snake.”
“In most of the Columbia Basin, western rattlesnakes emerge from their overwintering sites (hibernacula or dens) in April.”
“Adults return to the overwintering sites starting in late September, although activity may continue until late October depending on location and temperatures.”
“Rattlesnakes are active during the day when temperatures are moderate but switch to nocturnal activity during the hottest months of the year.”
Living with wildlife: Snakes. Washington Department of Fish and Wildlife. undated page; checked November 3, 2026.Quoted passages (6)
“All rattlesnake bites should be considered life threatening.”
“A bite from one of these nonvenomous snakes may be alarming, but will rarely break the skin.”
“Make sure the doctor who treats the victim knows how to treat snakebites and, if not, call the Poison Center at (800) 222-1222.”
“If you encounter a rattlesnake, move away:”
“Snakes should be left alone, and except for a rattlesnake that poses an immediate danger to people or pets, no snake should ever be killed.”
“Emergence from hibernation can begin as early as March, depending on the species and location.”
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