Which counties get the weather that wears this part?

FEMA's National Risk Index puts Tulsa County, OK, Shelby County, TN and Maricopa County, AZ highest for heat waves, about 26.26 events a year, against 5.39 in the median county. Heat waves push cooling systems toward overheating.

Tulsa County, OK26.26

Shelby County, TN21.74

Maricopa County, AZ19.83

Dallas County, TX19.11

Tarrant County, TX19.11

Pulaski County, AR18.68

Collin County, TX18.37

Cleveland County, OK18.26

Oklahoma County, OK18.16

Denton County, TX18.16

What it shows: Tulsa County, OK is the largest at 26.26, followed by Shelby County, TN at 21.74; the smallest shown is Oklahoma County, OK at 18.16.

Source: FEMA National Risk Index v1.20 (December 2025), county table: annualized frequency per hazard · file downloaded 2025-12