Climate Zones
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Climate Zone Descriptions

Use the table below to gain a better understanding of each climate zone.

Climate Zone
 Name

Thermal Criteria (SI)

Thermal Criteria (I-P)

 

1

Very Hot - Humid (1A), Dry (1B)

5000 < CDD10 C

9000 < CDD50ºF

 

2

Hot - Humid (2A), Dry (2B)

3500 < CDD10 C < 5000
6300 < CDD50ºF < 9000
 

3A,3B

Warm - Humid (3A), Dry (3B)

2500 < CDD10 C < 3500 4500 < CDD50ºF < 6300
 

3C

Warm - Marine (3C)

CDD10 C < 2500 &
HDD18 C < 2000
CDD50ºF < 4500 &
3600 < HDD65ºF < 5400
 

4A, 4b

Mixed - Humid (4A), Dry (4B)

2500 < CDD10 C &
2000 HDD18 C < 3000
3600 < HDD65ºF < 5400
 

4C

Mixed - Marine (4C)

2000 HDD18 C < 3000 5400 < HDD65ºF < 7200
 

5

Cool - Humid (5A), Dry (5B),
Marine (5C)

3000 HDD18 C < 4000 7200 < HDD65ºF < 9000
 

6

Cold - Humid (6A), Dry (6B)

4000 HDD18 C < 5000 9000 < HDD65ºF < 12600
 

7

Very Cold

5000 HDD18 C < 7000 R-35
 

8

Subarctic

7000 < HDD18 C 12600 < HDD65ºF