The worst time for ticks in Colorado is spring through early summer, roughly April through June. Unlike many eastern states where multiple tick species create overlapping seasons, Colorado’s tick problem is concentrated into a relatively short window driven by one dominant species: the Rocky Mountain wood tick.
Peak Season: Spring Through Early Summer
The Rocky Mountain wood tick accounts for almost all human tick encounters in Colorado. It becomes active as temperatures warm in spring, reaches peak activity by mid-spring, and then goes dormant once summer heat sets in. That dormancy pattern is unusual compared to ticks in other parts of the country, where warm weather ramps activity up rather than shutting it down. For Colorado hikers, this means the risk window is relatively compact but intense.
Most tick bites reported in the state happen during this spring-to-early-summer stretch. By July, encounters drop sharply. If you’re planning a backpacking trip in August or September, ticks are far less of a concern than they would be on that same trail in May.
Where You’re Most Likely to Pick One Up
Colorado’s tick geography is different from what many people expect. Ticks here are most common at higher elevations, not in low-lying river valleys or urban parks. The brushy edges where fields meet woodlands are prime habitat, along with well-traveled paths through grass and shrubland. Think of the transition zones: trails that cut through scrub oak, meadow borders, and areas where deer and elk move regularly.
Tick density is highest near animal hosts. If a trail shows signs of heavy wildlife use, especially by deer or elk, expect ticks to be concentrated along that corridor. They position themselves on grass tips and low brush, waiting for something warm-blooded to brush past.
Tick-Borne Illness in Colorado
Colorado tick fever is the state’s signature tick-borne disease, transmitted by the Rocky Mountain wood tick. Despite the name, Rocky Mountain spotted fever is actually rare in Colorado. Colorado tick fever is a viral infection that typically causes high fever, severe headache, body aches, and fatigue. Symptoms often follow a distinctive pattern where fever breaks, you feel better for a day or two, then the fever returns. Most people recover fully, but the illness can knock you out for several weeks.
Because the tick responsible goes dormant in summer, the transmission window for Colorado tick fever aligns exactly with peak tick activity: spring and early summer. A tick generally needs to be attached for several hours before it can transmit the virus, which is why prompt tick checks matter so much during these months.
How to Protect Yourself During Peak Season
Clothing is your first line of defense. Long pants tucked into socks and long sleeves reduce the skin available for a tick to latch onto. Treating clothing with permethrin adds a powerful layer of protection. Pre-treated clothing (or garments you send to a professional service) maintains its effectiveness through about 70 washes. If you spray your own clothes at home, the treatment lasts roughly 6 washes or 6 weeks, whichever comes first. Always spray clothing while it’s off your body and let it dry completely before wearing it.
On exposed skin, use an EPA-registered insect repellent. After any spring or early summer hike at elevation, shower within two hours and do a thorough tick check. Pay attention to hidden spots: behind your ears, along your hairline, behind your knees, around your waistband, and in your armpits. Check your dog too, since Rocky Mountain wood ticks readily bite pets.
Removing a Tick the Right Way
If you find an attached tick, use fine-tipped tweezers or a tick removal tool. Grip the tick as close to your skin as possible and pull straight up with steady, even pressure. Don’t twist, crush, or jerk it. Wash the bite area with soap and water and apply antiseptic cream. If the mouthparts break off in the skin, don’t panic. They may cause some local irritation but will work their way out on their own.
Skip the folk remedies. Holding a match or cigarette to a tick, smothering it with petroleum jelly, or dousing it with alcohol doesn’t work and can actually cause the tick to release more saliva into your skin. After removal, watch the bite site for the next few weeks. A pink or red rash spreading around the bite, a fever above 100.4°F, flu-like symptoms such as headache or joint pain, or swollen lymph nodes all warrant a call to your doctor.
Late Summer and Fall: A Different Tick
Colorado does have a second tick cycle worth knowing about. The winter tick, a different species, hatches in late summer and early autumn. But this tick primarily feeds on large wildlife like moose and elk, not humans. It’s not a significant bite risk for hikers. By the time fall rolls around, the Rocky Mountain wood tick is long dormant, and the overall risk of a human tick encounter in Colorado drops to its lowest point of the year.