Tick Season in Colorado: What to Know to Stay Safe Outdoors

Colorado’s trails, foothills, and open spaces are some of the most beautiful in the country — and they come with a small but serious hazard that every outdoor enthusiast should understand. If you spend time in Colorado’s outdoors, tick season is something you need to plan around, not just react to.

Tick activity in Colorado tends to peak during the spring and early summer months, although ticks can be active all year round. Whether you’re hiking Rocky Mountain National Park, camping in the foothills, or simply letting your dog roam the backyard, understanding tick season in Colorado gives you a real advantage in keeping your family safe.

Key Insight: Ticks don’t just live in deep wilderness. They’re commonly found in suburban yards, neighborhood parks, and along popular trail edges — making awareness important for all Coloradans, not just backcountry hikers.

When Is Tick Season in Colorado

Tick season usually starts in March and reaches its peak in May and June, making this the worst time for ticks in Colorado. Their numbers and activity tend to die back by the end of summer or early fall. That said, you shouldn’t let your guard down entirely once summer heats up.

In Colorado, recent months of soggy weather could spell a long season ahead, which typically fades during hotter summer months and undergoes another surge, though generally smaller, in the fall. Tick peak activity in Colorado peaks from late April through mid-July. This is the window when you need to be most vigilant.

Tick season extends from April through October or even November, so preventives should be given through those months — especially for pets that spend time outdoors regularly. The Rocky Mountain wood tick is most active and bites most in spring, becoming dormant with warm weather in summer.

Important Note: Even outside of peak season, ticks can remain active on warm winter days. Year-round vigilance — especially for your pets — is the safest approach in Colorado.

Types of Ticks Found in Colorado

Colorado is home to approximately 30 different species of ticks. While that number sounds alarming, the good news is that most human encounters involve only a handful of species. Almost all human encounters with ticks in Colorado involve the Rocky Mountain wood tick. Fortunately, some of the most important tick species present elsewhere in the United States are either rare (lone star tick) or completely absent from the state (blacklegged tick).

Two families of ticks occur in Colorado: hard ticks (Ixodidae family) and soft ticks (Argasidae family). Hard ticks can be distinguished by the presence of a plate (scutellum) on the back behind the head. They also have mouthparts that are directed forward and are easily visible. The soft ticks lack the plate, have a less regularly rounded body, and have mouthparts that are directed beneath the tick, so they are not visible from above.

Here are the key species you’re most likely to encounter in Colorado:

Tick Species	Family	Primary Habitat	Peak Activity	Disease Risk
Rocky Mountain Wood Tick	Hard tick	Wooded areas, subalpine shrublands	Spring (March–June)	Colorado tick fever, Rocky Mountain spotted fever, tick paralysis
American Dog Tick	Hard tick	Grassy fields, roadsides, suburban areas	Spring–Summer	Rocky Mountain spotted fever, tularemia
Brown Dog Tick	Hard tick	Kennels, homes with dogs	Year-round indoors	Rocky Mountain spotted fever (rare)
Soft Tick (Ornithodoros hermsi)	Soft tick	Rodent nests, rustic cabins at elevation	Year-round	Tick-borne relapsing fever

As its name suggests, the Rocky Mountain wood tick is commonly found in wooded areas and shrublands throughout Colorado. They are generally subalpine, but have been found in alpine locations as well. These ticks are especially hardy and can survive for up to two years without a single meal.

Tick-borne relapsing fever is caused by bacteria transmitted from the bite of soft ticks (commonly Ornithodoros hermsi in Colorado), which are often found in rodent nests associated with rustic cabins in forested high-elevation habitats. If you’re staying in an older mountain cabin, this is a species worth knowing about.

To better understand how ticks reproduce and complete their life cycle, it helps to know that ticks go through four life stages as they develop. Eggs are laid in large masses that often total thousands of eggs. At hatch, there is a tiny larva (“seed tick”) that is six-legged. After it has fed and developed, it will molt to an eight-legged nymph. When this has fed and developed, it will molt to the final stage adult.

Tick-Borne Diseases in Colorado

Ticks in Colorado can carry diseases such as Colorado tick fever, tick-borne relapsing fever, tularemia, and Rocky Mountain spotted fever. Each disease has its own set of symptoms and risks, so knowing what to watch for after a bite can make a meaningful difference in how quickly you get the right care.

Colorado tick fever is by far the most common tick-transmitted disease of the region. It is an uncommon disease spread by the bite of an infected Rocky Mountain wood tick found in the western United States and western Canada. Colorado tick fever presents clinically with a sudden onset of fever (up to 40°C), commonly in conjunction with headache, chills, myalgia, and/or photophobia. The characteristic biphasic fever involves sudden onset of fever, typically 3–6 days after a tick bite, followed by a remission for 2 days, and a recurrence of symptoms for 1–2 days.

Colorado tick fever symptoms include fever, chills, headache, body aches, and feeling tired. Some patients have sore throat, vomiting, abdominal pain, or skin rash. About half of patients have several days of fever, feel better for several days, then have a second short period of fever and illness. Weakness and fatigue may last several weeks, but most people recover completely. In rare cases, severe illness affecting the central nervous system may occur.

Tick-borne relapsing fever (TBRF) presents with high fever (e.g., 103°F), headache, and muscle and joint aches. For bacterial diseases such as Rocky Mountain spotted fever and tularemia, doctors have antibiotics for treatment. Viral diseases such as Colorado tick fever can be treated only symptomatically.

Important Note: While Lyme disease is not currently established in Colorado’s wild animal population, it’s worth knowing about if you travel. One of the most well-known tick-borne diseases, Lyme disease, is NOT present in Colorado’s wild animal population. Lyme disease ticks are primarily found in the northeastern U.S.

The onset of symptoms for tick-borne diseases can range from days to as long as four weeks. If you’ve had a tick bite and develop any flu-like symptoms within that window, contact your healthcare provider and mention the exposure. You can also read more about tick-borne encephalitis to understand the broader range of neurological risks associated with tick-borne viruses globally.

Symptoms may be subtle and feel like the flu. You may have body aches, fever, and chills. Your joints may feel terrible. But then it’s gone. This pattern — especially the relapsing fever — is a hallmark of several Colorado tick diseases and should prompt a call to your doctor.

High-Risk Areas and Habitats in Colorado

Ticks are most active in spring and early summer and concentrate where their animal hosts most commonly travel. This includes brushy areas along the edges of fields and woodlands or commonly traveled paths through grassy areas and shrublands. Colorado’s extensive trail networks, attracting millions of visitors annually, serve as critical habitats for ticks.

Colorado tick fever occurs in people who live in or visit areas where there are infected Dermacentor andersoni ticks. These ticks are found in the western United States or western Canada at elevations of 4,000–10,000 feet above sea level. This means that popular mountain destinations — think Rocky Mountain National Park, the Pike National Forest, and the San Juan Mountains — are all areas where elevated tick risk applies.

You don’t have to be in the backcountry to encounter ticks, though. Ticks are found throughout the entire state, hanging on leaves, grass, and other vegetation, waiting for an unsuspecting host to brush up against them. However, their population density can vary substantially from one location to another. Wooded areas, fields, gardens, shrubland, and other grassy areas have the largest concentration of ticks. You may even find some in your own yard.

Common Mistake: Many people assume ticks only live deep in forests. In reality, ticks tend to be at the tops of grasses or brush, ready to latch onto a passing host. They are attracted by heat, body odor, carbon dioxide, and movement. Even a neighborhood walk through tall grass carries some risk during peak season.

Hunters are at particular risk, as exposure to tick habitat is higher, as well as handling of potentially infected animals such as rabbits, muskrats, prairie dogs, and other rodents. If you’re spending time in the field during dove hunting season in Colorado or other outdoor pursuits, be especially diligent about tick checks in grassy, brushy terrain.

High-risk counties in Colorado include areas with documented tick-borne disease activity. Among the 26 counties that reported human tularemia cases between 2012 and 2017, Boulder, Larimer, and Weld counties were three of the highest reporting counties. The Front Range foothills and mountain corridors consistently see the most tick activity each spring.

How to Protect Yourself, Children and Pets During Tick Season in Colorado

Prevention is your most powerful tool against tick-borne illness. The best way to prevent tick-borne illnesses is to prevent tick bites. By keeping ticks away from your body, you are less likely to be bitten and get sick from a tick bite. A few consistent habits can significantly reduce your risk throughout the season.

Protective Clothing and Repellents

• Wear long-sleeved, light-colored clothing. Tuck your pant legs into your socks and your shirt into your pants.
• Use repellents recommended for ticks, including DEET, picaridin, IR3535, and oil of lemon eucalyptus.
• Consider permethrin-treated clothing for extended outdoor activities — it remains effective through multiple washes.
• Stay on trails and avoid brushy areas, since ticks often attach after climbing to the end of vegetation.

After Being Outdoors

• Take a shower within two hours after spending time outdoors, which will wash off any unattached ticks.
• As soon as you’re home, throw your clothes in the dryer on high heat for 20 minutes to dislodge or kill any ticks.
• Ticks like warm, moist areas, so pay special attention to your armpits, knees, groin area, and scalp during your post-outdoor tick check.
• Check for ticks regularly while you are hiking or spending time outside, especially in areas with high grass, or after sitting on rocks or logs.

Protecting Children

Children are often closer to ground-level vegetation and may not notice a tick crawling on them. Dress kids in long sleeves and pants during outdoor activities, apply EPA-approved repellents appropriate for their age, and perform a thorough head-to-toe tick check at bath time. Pay close attention to the hairline, behind the ears, and the back of the neck.

Pro Tip: Make tick checks a routine part of post-outdoor cleanup for the whole family. A simple full-body check, especially in warm skin folds, takes only a few minutes and can catch a tick before it has time to transmit disease.

Protecting Your Pets

Dogs and cats can bring ticks into your home without showing obvious signs of a bite. If your pet goes outdoors, be sure to give a monthly flea and tick preventive like Nexgard or Frontline Gold. Tick season extends from April through October or even November, so preventives should be given through those months.

Give yourself and your pets a check before returning inside, especially after being near heavily wooded areas. Ticks like warm, moist areas, so pay special attention to your pet’s head, neck, ears, and feet. For more detailed guidance, see these tips for preventing tick-borne diseases in your dog. You might also be interested to learn about animals that naturally eat ticks, which can help reduce tick populations in your yard.

Increase sunlight in your yard by pruning the lower branches of trees or thinning out shrubs and hedges. This will cause ticks to dry out and die. Keep your lawn mowed to 3 inches or less. This lowers the humidity at ground level, making it difficult for ticks to survive.

What to Do If You Find a Tick in Colorado

Finding a tick on yourself, your child, or your pet can be unsettling, but a calm and methodical approach is all you need. If you find a tick attached to your skin, remove it as quickly — and carefully — as possible to reduce the chance of infection. Speed matters: some viruses can transmit in as quickly as 15 minutes after the tick has attached.

Step-by-Step Tick Removal

1. Use the right tool. While there are many tick removal devices available, a pair of fine-tipped tweezers or a tick removal spoon work best.
2. Grasp correctly. Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible.
3. Pull steadily. Pull upward with steady, even pressure. Avoid twisting or jerking the tick, as this can cause parts to break off and remain embedded in the skin.
4. Clean the area. After removal, clean the bite area and your hands with rubbing alcohol, iodine scrub, or soap and water.
5. Dispose of the tick safely. Dispose of the tick by placing it in a sealed container, submerging it in alcohol, or wrapping it tightly in tape. Consider saving it in a sealed container, labeled with a date, location, and time of removal, in case testing is needed later.

Common Mistake: Do NOT crush the tick’s body or attempt to burn or smother it — this can increase the risk of disease transmission. Similarly, do not use petroleum jelly, a hot match, dish soap, nail polish, or other folk remedies to remove ticks. They are generally not effective and may increase the risk of infection.

After removing the tick, monitor your health closely. If you find a tick on your body and are unsure how long it’s been there, monitor for symptoms such as fever, chills, headache or body aches, nausea, abdominal pain, and fatigue. If you are experiencing any of these symptoms, reach out to your healthcare provider as soon as possible for an evaluation.

If you find a tick that looks plump and fat, this is a tick that has been feeding and has more potential to spread disease. You should contact your health professional (for yourself) or your veterinarian (for your pet) to discuss next steps.

Reporting Tick Bites and Tick-Borne Illness in Colorado

Reporting your tick encounter isn’t just good for your own health — it actively helps Colorado public health officials track tick populations and disease risk across the state. The Colorado Department of Public Health and Environment (CDPHE) wants your ticks. Visit the CDPHE’s Citizen Scientist Tick Surveillance Project to submit your tick to help better understand what types of ticks exist in the state and where they are located. An entomologist will determine the species of the submitted tick. Ticks will not be tested for diseases.

A community science program for tick surveillance at trailheads, where people and their companions are most likely to encounter ticks, may be an effective approach for improving our understanding of tick distributions and tick-borne disease risk in Colorado. Collection stations have been deployed at trailheads in Larimer and Boulder counties as part of this growing effort.

If you want a tick tested for pathogens specifically, third-party services like TickCheck.com offer laboratory testing directly to the public. This can provide peace of mind, particularly if the tick was engorged or attached for an unknown length of time.

Key Insight: At the Colorado Department of Public Health and Environment, there is a vector-borne disease coordinator who can help with questions and testing coordination. Many other states also have such coordinators. Sometimes state labs can test samples; sometimes they send them to the CDC.

If you develop symptoms of a tick-borne illness after a bite, see a healthcare provider promptly and mention the tick exposure, where you were, and approximately when the bite occurred. For bacterial diseases such as Rocky Mountain spotted fever and tularemia, doctors have antibiotics for treatment — and early treatment significantly improves outcomes. Tularemia is a reportable disease in Colorado, meaning your doctor is required to notify the state health department if you’re diagnosed, which helps officials monitor and respond to outbreaks.

Staying informed and taking simple, consistent precautions makes tick season in Colorado entirely manageable. Whether you’re heading out for a trail run in the Front Range foothills or spending a weekend at a mountain cabin, a little preparation goes a long way toward keeping you, your children, and your pets safe all season long.

This information is for educational purposes only and is not intended as medical advice. Always consult with a qualified healthcare professional before making health decisions related to tick bites or tick-borne illness.