Pennsylvania heat wave risk
Philadelphia County has the highest heat wave risk in Pennsylvania, scoring 100 out of 100 — rated "Very High" by FEMA's National Risk Index. Recorded heat wave events across Pennsylvania have increased 263% over the past five years compared to the prior five-year period.
| # | County | NRI score | Rating |
NOAA events 2016–2026 |
|---|---|---|---|---|
| 1 | Philadelphia County | 100 | Very High | 20 |
| 2 | Montgomery County | 98.3 | Relatively High | 12 |
| 3 | Delaware County | 97.6 | Relatively High | 14 |
| 4 | Lehigh County | 96.5 | Relatively Moderate | 5 |
| 5 | Chester County | 95.6 | Relatively Moderate | 9 |
| 6 | Bucks County | 95.1 | Relatively Moderate | 11 |
| 7 | Berks County | 94.5 | Relatively Moderate | 6 |
| 8 | Lancaster County | 94.4 | Relatively Moderate | 7 |
| 9 | Allegheny County | 94.3 | Relatively Moderate | 1 |
| 10 | Northampton County | 94.1 | Relatively Moderate | 4 |
| 11 | York County | 91.8 | Relatively Moderate | 5 |
| 12 | Luzerne County | 91.3 | Relatively Moderate | 0 |
| 13 | Dauphin County | 88.4 | Relatively Moderate | 6 |
| 14 | Cumberland County | 85.6 | Relatively Moderate | 5 |
| 15 | Lackawanna County | 83.6 | Relatively Moderate | 0 |
| 16 | Carbon County | 82.1 | Relatively Moderate | 0 |
| 17 | Lebanon County | 75.7 | Relatively Low | 6 |
| 18 | Monroe County | 74.7 | Relatively Low | 0 |
| 19 | Perry County | 74.5 | Relatively Low | 4 |
| 20 | Schuylkill County | 74.3 | Relatively Low | 1 |
| 21 | Franklin County | 72.1 | Relatively Low | 4 |
| 22 | Adams County | 68.6 | Relatively Low | 5 |
| 23 | Westmoreland County | 59.9 | Relatively Low | 0 |
| 24 | Northumberland County | 59.2 | Relatively Low | 2 |
| 25 | Columbia County | 52.5 | Relatively Low | 1 |
| 26 | Lycoming County | 52.5 | Relatively Low | 1 |
| 27 | Centre County | 48 | Relatively Low | 1 |
| 28 | Washington County | 47.8 | Relatively Low | 0 |
| 29 | Beaver County | 45.7 | Relatively Low | 0 |
| 30 | Union County | 44.7 | Relatively Low | 1 |
| 31 | Fayette County | 44.1 | Relatively Low | 0 |
| 32 | Snyder County | 43.6 | Relatively Low | 3 |
| 33 | Mifflin County | 42.7 | Relatively Low | 3 |
| 34 | Butler County | 41.1 | Relatively Low | 0 |
| 35 | Blair County | 40.9 | Relatively Low | 1 |
| 36 | Erie County | 40.6 | Relatively Low | 0 |
| 37 | Pike County | 39.9 | Relatively Low | 0 |
| 38 | Juniata County | 37.7 | Very Low | 3 |
| 39 | Bradford County | 32.7 | Very Low | 0 |
| 40 | Indiana County | 32.1 | Very Low | 0 |
| 41 | Wayne County | 32 | Very Low | 0 |
| 42 | Bedford County | 31.1 | Very Low | 1 |
| 43 | Armstrong County | 30.8 | Very Low | 0 |
| 44 | Lawrence County | 29.4 | Very Low | 0 |
| 45 | Wyoming County | 29.2 | Very Low | 0 |
| 46 | Mercer County | 28.4 | Very Low | 0 |
| 47 | Huntingdon County | 28.1 | Very Low | 1 |
| 48 | Montour County | 27.1 | Very Low | 1 |
| 49 | Crawford County | 24.9 | Very Low | 0 |
| 50 | Clinton County | 24.3 | Very Low | 1 |
| 51 | Susquehanna County | 24.1 | Very Low | 0 |
| 52 | Greene County | 22.5 | Very Low | 0 |
| 53 | Cambria County | 21.7 | Very Low | 0 |
| 54 | Somerset County | 20.3 | Very Low | 0 |
| 55 | Fulton County | 18 | Very Low | 1 |
| 56 | Clearfield County | 17.5 | Very Low | 0 |
| 57 | Tioga County | 15.9 | Very Low | 1 |
| 58 | Venango County | 15 | Very Low | 0 |
| 59 | Jefferson County | 13.7 | Very Low | 0 |
| 60 | Clarion County | 12.3 | Very Low | 0 |
| 61 | McKean County | 10.5 | Very Low | 0 |
| 62 | Warren County | 9.7 | Very Low | 0 |
| 63 | Elk County | 7.9 | Very Low | 0 |
| 64 | Sullivan County | 6.9 | Very Low | 1 |
| 65 | Potter County | 6.6 | Very Low | 0 |
| 66 | Forest County | 4.4 | Very Low | 0 |
| 67 | Cameron County | 3.4 | Very Low | 0 |
Source: FEMA National Risk Index v1.20.0, December 2025. Scores are 0–100 percentile rankings among all US counties. See the methodology page for definitions. Download the full CSV for all counties.
Heat Wave risk nationally:
Other hazard risks in Pennsylvania:
Frequently asked questions
What is the highest heat wave risk county in Pennsylvania?
Philadelphia County, PA has the highest heat wave risk in Pennsylvania, with a FEMA National Risk Index score of 100 out of 100 (rated "Very High").
How many counties in Pennsylvania are rated Very High for heat wave risk?
1 of 67 scored Pennsylvania counties are rated "Very High" for heat wave risk by FEMA's National Risk Index.
What causes heat wave risk in Pennsylvania?
Heat is consistently the leading cause of weather-related mortality in the US, yet it remains underrepresented in federal disaster declarations relative to its actual impact. High scores reflect a combination of extreme temperature exposure, population vulnerability (elderly, outdoor workers), and limited access to cooling infrastructure.