Maryland climate zones
Maryland’s 24 counties fall in 2 IECC 2021 climate zones: 4A (22), 5A (2).
Zone 4A: mixed-humid
Attic target R60 (ENERGY STAR)Anne Arundel County (Mixed-humid) · Baltimore City (Mixed-humid) · Baltimore County (Mixed-humid) · Calvert County (Mixed-humid) · Caroline County (Mixed-humid) · Carroll County (Mixed-humid) · Cecil County (Mixed-humid) · Charles County (Mixed-humid) · Dorchester County (Mixed-humid) · Frederick County (Mixed-humid) · Harford County (Mixed-humid) · Howard County (Mixed-humid) · Kent County (Mixed-humid) · Montgomery County (Mixed-humid) · Prince George's County (Mixed-humid) · Queen Anne's County (Mixed-humid) · Somerset County (Mixed-humid) · St. Mary's County (Mixed-humid) · Talbot County (Mixed-humid) · Washington County (Mixed-humid) · Wicomico County (Mixed-humid) · Worcester County (Mixed-humid)
Zone 5A: cool-humid
Attic target R60 (ENERGY STAR)Allegany County (Cold) · Garrett County (Cold)