Climate Zone 3A - Warm, Humid
Warm summers with humidity. Moderate heating and cooling needs throughout the year. This climate zone encompasses parts of North Carolina, South Carolina, Georgia, Alabama, Tennessee, Arkansas, Virginia and includes major cities like Atlanta, Charlotte, Memphis, Birmingham.
Common Questions About Zone 3A
Zone 3A definition
This page explains what IECC climate zone 3A means in HVAC and building-code terms.
Cities in zone 3A
Use the city examples below to answer common lookup searches for this zone.
Heating and cooling profile
See whether zone 3A is heating-dominant, cooling-dominant, or balanced.
HVAC requirements
Compare design temperatures, degree days, code requirements, and equipment guidance for this zone.
What IECC Climate Zone 3A Means
Temperature class
Warm (Zone 3)
Moisture class
Moist (A)
Load priority
Heating-dominant
Quick definition
Warm summers with humidity. Moderate heating and cooling needs throughout the year.
Common City Lookups for Zone 3A
| City | IECC zone answer | Why it matters |
|---|---|---|
| Atlanta | Atlanta is commonly treated as IECC climate zone 3A in this guide. | Balanced heating and cooling loads |
| Charlotte | Charlotte is commonly treated as IECC climate zone 3A in this guide. | Balanced heating and cooling loads |
| Memphis | Memphis is commonly treated as IECC climate zone 3A in this guide. | Balanced heating and cooling loads |
| Birmingham | Birmingham is commonly treated as IECC climate zone 3A in this guide. | Balanced heating and cooling loads |
| Little Rock | Little Rock is commonly treated as IECC climate zone 3A in this guide. | Balanced heating and cooling loads |
Design Temperatures
Winter Design Temperatures
Used for heating load calculations and equipment sizing
Summer Design Temperatures
Used for cooling load calculations and equipment sizing
Heating & Cooling Degree Days
Heating Degree Days (HDD)
Base 65°F. Higher numbers indicate more heating requirements and longer heating seasons.
Cooling Degree Days (CDD)
Base 65°F. Higher numbers indicate more cooling requirements and longer cooling seasons.
HVAC System Considerations
Key Considerations
- •Balanced heating and cooling loads
- •Humidity control important
- •Moderate equipment sizing
- •Seasonal changeover systems
- •Mold prevention
Common Equipment
- ✓Heat pumps
- ✓Gas furnaces with AC
- ✓Dual-fuel systems
- ✓Variable speed equipment
Energy Code Requirements
Equipment Efficiency
- ⚠SEER 13+ minimum
- ⚠HSPF 7.7+ for heat pumps
- ⚠AFUE 80+ for furnaces
- ⚠Duct insulation R-6 minimum
Insulation Requirements
Major Cities in Zone 3A
States with Zone 3A Areas
Quick Reference
Calculate Load
Use our load calculators with the design temperatures and requirements specific to Zone 3A.