When Is Deer Tick Season? When Lyme Disease Risk Is Highest

When is deer tick season—and when is Lyme disease risk highest? The answer depends on the tick’s life stage, but the greatest risk occurs in late spring and early summer when tiny nymph ticks are most active.

A patient came to my office in June with a bull’s-eye rash. “I checked myself after hiking,” she said, “but I never saw a tick.”

She had been bitten by a nymph—about the size of a poppy seed—small enough to go unnoticed but fully capable of transmitting Lyme disease.

This is typical of deer tick season, when Lyme disease risk is at its peak.

When Deer Tick Season Peaks

Tick activity follows a predictable seasonal pattern:

Nymphs are most active from mid-May through mid-July.

• About 1–2 mm in size (poppy seed)
• Hard to detect
• Responsible for most infections

Adult deer ticks are active in spring and fall whenever temperatures exceed 45°F.

• Larger (sesame seed size)
• Easier to detect—but still often missed

Risk peaks in late spring and early summer—but exposure can occur year-round.

Why the Nymph Stage Drives Most Infections

Up to 70% of Lyme disease cases are linked to nymph ticks.

Because they are so small, they often remain attached long enough to transmit infection.

Although transmission is often described as requiring 36–48 hours, it may occur sooner—especially when co-infections such as Babesia or Anaplasma are involved.

Most people underestimate how long a tick has been attached.

Where Deer Ticks Are Found

Ticks are not limited to wooded areas.

They are commonly found in:

• Suburban yards
• Gardens
• Parks
• Leaf litter and tall grass

You don’t need to go hiking to be exposed.

Even routine activities—gardening, walking your dog, or playing outside—can lead to tick exposure.

Regional Differences in Deer Tick Season

• Northeast & Upper Midwest: April–October (peak May–July)
• Mid-Atlantic: Late May–early August peak
• Southern States: Year-round risk
• Northern States: Activity pauses in frost but rebounds quickly

Climate change is extending tick season across the U.S.

Should You Take Antibiotics After a Tick Bite?

The CDC recommends a single dose of doxycycline in specific situations.

However, some patients still develop Lyme disease despite prophylaxis.

Early symptom recognition remains critical.

Learn more about tick transmission timing.

What To Do After a Tick Bite

• Remove the tick promptly
• Monitor for rash or symptoms
• Seek evaluation if symptoms develop

Early treatment significantly improves outcomes.

Clinical Takeaway

Deer tick season peaks in late spring and early summer—when nymph ticks are most active.

• Risk is highest May–July
• Nymph ticks cause most infections
• Exposure occurs in everyday environments

Understanding tick season helps prevent Lyme disease.

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention