Ticks in Pennsylvania

Ticks are active in Pennsylvania whenever the ground is not frozen, led by the Lyme-carrying deer tick. TickZone scores all 2571 Pennsylvania towns every morning, so risk stays local: pick your town for today's number, a 7-day outlook, and what's driving it.

Tick season in Pennsylvania

Tick season in Pennsylvania runs whenever the ground is not frozen, roughly March through November, with two peaks. Nymph deer ticks, the poppy-seed-sized stage that causes most Lyme cases, peak from late May through July. Adult deer ticks make a second push in October and November, and on any winter day above about 40 F they can quest again. American dog ticks are busiest from April through July.

Generalized for the Northeast and Upper Midwest Lyme belt.
Life stageJFMAMJJASOND
Deer tick nymphs
Deer tick adults
American dog tick
Lone star tick
Peak Active
Generalized for the Northeast and Upper Midwest Lyme belt. Activity windows by life stage from TickEncounter (Univ. of Rhode Island) and the Northeast Regional Center for Excellence in Vector-Borne Diseases. Any warm spell can wake ticks earlier than the calendar suggests.

Those are averages, and any single week can run hotter or colder than the calendar suggests. The daily score on every town page folds the season, the weather, and local habitat into one number each morning, so it is the safer way to time yard work, hikes, and pet prevention.

Highest-risk towns in Pennsylvania (2026)

Pennsylvania's highest structural tick risk concentrates in Potter County, which holds 7 of the state's top 10 towns (550 CDC-reported Lyme cases per 100k). The top 10 towns run 95 to 99 percent forest, ranked at peak season so the list stays stable.

  1. 1Stewardson Township Potter CountyHigh at peak
  2. 2Portage Township Potter CountyHigh at peak
  3. 3Wharton Township Potter CountyHigh at peak
  4. 4Grove Township Cameron CountyHigh at peak
  5. 5Heath Township Jefferson CountyHigh at peak
  6. 6Barnett Township Jefferson CountyHigh at peak
  7. 7Austin Borough Potter CountyHigh at peak
  8. 8Sylvania Township Potter CountyHigh at peak
  9. 9Summit Township Potter CountyHigh at peak
  10. 10Pike Township Potter CountyHigh at peak

See the riskiest towns in every state →

All Pennsylvania towns, by county

Adams County · 34 towns · 135/100k Lyme

Allegheny County · 130 towns · 69/100k Lyme

Armstrong County · 45 towns · 286/100k Lyme

Beaver County · 54 towns · 73/100k Lyme

Bedford County · 38 towns · 117/100k Lyme

Berks County · 73 towns · 99/100k Lyme

Blair County · 25 towns · 150/100k Lyme

Bradford County · 51 towns · 152/100k Lyme

Bucks County · 54 towns · 82/100k Lyme

Butler County · 57 towns · 175/100k Lyme

Cambria County · 63 towns · 208/100k Lyme

Cameron County · 7 towns · 537/100k Lyme

Carbon County · 23 towns · 21/100k Lyme

Centre County · 35 towns · 169/100k Lyme

Chester County · 73 towns · 140/100k Lyme

Clarion County · 35 towns · 315/100k Lyme

Clearfield County · 50 towns · 331/100k Lyme

Clinton County · 29 towns · 117/100k Lyme

Columbia County · 33 towns · 96/100k Lyme

Crawford County · 51 towns · 298/100k Lyme

Cumberland County · 33 towns · 80/100k Lyme

Dauphin County · 40 towns · 70/100k Lyme

Delaware County · 49 towns · 62/100k Lyme

Elk County · 12 towns · 333/100k Lyme

Erie County · 38 towns · 78/100k Lyme

Fayette County · 43 towns · 126/100k Lyme

Forest County · 9 towns · 395/100k Lyme

Franklin County · 22 towns · 70/100k Lyme

Fulton County · 13 towns · 156/100k Lyme

Greene County · 26 towns · 205/100k Lyme

Huntingdon County · 48 towns · 202/100k Lyme

Indiana County · 38 towns · 195/100k Lyme

Jefferson County · 34 towns · 552/100k Lyme

Juniata County · 17 towns · 140/100k Lyme

Lackawanna County · 40 towns · 76/100k Lyme

Lancaster County · 60 towns · 80/100k Lyme

Lawrence County · 27 towns · 92/100k Lyme

Lebanon County · 26 towns · 105/100k Lyme

Lehigh County · 25 towns · 13/100k Lyme

Luzerne County · 76 towns · 54/100k Lyme

Lycoming County · 52 towns · 110/100k Lyme

McKean County · 22 towns · 352/100k Lyme

Mercer County · 48 towns · 129/100k Lyme

Mifflin County · 16 towns · 139/100k Lyme

Monroe County · 20 towns · 53/100k Lyme

Montgomery County · 62 towns · 66/100k Lyme

Montour County · 11 towns · 112/100k Lyme

Northampton County · 38 towns · 31/100k Lyme

Northumberland County · 36 towns · 64/100k Lyme

Perry County · 30 towns · 249/100k Lyme

Philadelphia County · 1 towns

Pike County · 13 towns · 216/100k Lyme

Potter County · 30 towns · 550/100k Lyme

Schuylkill County · 67 towns · 52/100k Lyme

Snyder County · 21 towns · 69/100k Lyme

Somerset County · 50 towns · 206/100k Lyme

Sullivan County · 13 towns · 189/100k Lyme

Susquehanna County · 40 towns · 352/100k Lyme

Tioga County · 39 towns · 173/100k Lyme

Union County · 14 towns · 107/100k Lyme

Venango County · 31 towns · 320/100k Lyme

Warren County · 27 towns · 357/100k Lyme

Washington County · 66 towns · 127/100k Lyme

Wayne County · 28 towns · 411/100k Lyme

Westmoreland County · 65 towns · 203/100k Lyme

Wyoming County · 23 towns · 230/100k Lyme

York County · 72 towns · 109/100k Lyme

Pennsylvania tick questions

Are there ticks in Pennsylvania?
Yes. Pennsylvania has ticks in every county, led by the deer tick (blacklegged tick) that spreads Lyme disease, along with the American dog tick and the lone star tick. They are active whenever the ground is not frozen, and today 2410 of the state's 2571 towns are at moderate or high tick risk on TickZone's daily score.
What types of ticks live in Pennsylvania?
Pennsylvania has the deer tick (blacklegged tick), which carries Lyme disease; the American dog tick; and the lone star tick, which is established in the state and causes alpha-gal syndrome. See the Pennsylvania tick identification chart for photos and how to tell them apart.
When does tick season start and end in Pennsylvania?
In Pennsylvania, ticks are active whenever the ground is not frozen, roughly March through November. Nymph deer ticks peak in June and July and cause most Lyme cases, and adult ticks have a second peak in the fall. On any winter day above freezing, adult ticks can still bite.
When is flea and tick season?
Flea and tick season generally runs from early spring through late fall, peaking in the warm summer months. In Pennsylvania, start prevention for pets and people in March and keep it up through November, since ticks can bite on any mild day.
Which tick carries Lyme disease in Pennsylvania?
The deer tick, also called the blacklegged tick, is the tick that spreads Lyme disease in Pennsylvania. The American dog tick and lone star tick do not carry Lyme.