Climate Zone 3B - Warm, Dry
Warm summers with low humidity. Cool winters requiring moderate heating. This climate zone encompasses parts of California, Texas, Oklahoma, New Mexico and includes major cities like Fresno, Austin, San Antonio, Lubbock.
Common Questions About Zone 3B
Zone 3B definition
This page explains what IECC climate zone 3B means in HVAC and building-code terms.
Cities in zone 3B
Use the city examples below to answer common lookup searches for this zone.
Heating and cooling profile
See whether zone 3B 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 3B Means
Temperature class
Warm (Zone 3)
Moisture class
Dry (B)
Load priority
Heating-dominant
Quick definition
Warm summers with low humidity. Cool winters requiring moderate heating.
Common City Lookups for Zone 3B
| City | IECC zone answer | Why it matters |
|---|---|---|
| Fresno | Fresno is commonly treated as IECC climate zone 3B in this guide. | Moderate cooling loads |
| Austin | Austin is commonly treated as IECC climate zone 3B in this guide. | Moderate cooling loads |
| San Antonio | San Antonio is commonly treated as IECC climate zone 3B in this guide. | Moderate cooling loads |
| Lubbock | Lubbock is commonly treated as IECC climate zone 3B in this guide. | Moderate cooling loads |
| Amarillo | Amarillo is commonly treated as IECC climate zone 3B in this guide. | Moderate 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
- •Moderate cooling loads
- •Heating needs in winter
- •Low humidity year-round
- •Temperature swings
- •Dust considerations
Common Equipment
- ✓Heat pumps
- ✓Gas furnaces with AC
- ✓Packaged units
- ✓Evaporative cooling (supplemental)
Energy Code Requirements
Equipment Efficiency
- ⚠SEER 13+ minimum
- ⚠HSPF 7.7+ for heat pumps
- ⚠AFUE 78+ for furnaces
- ⚠Window U-factor limits
Insulation Requirements
Major Cities in Zone 3B
States with Zone 3B Areas
Quick Reference
Calculate Load
Use our load calculators with the design temperatures and requirements specific to Zone 3B.