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The climate zone for any location outside the United States shall be determined by applying Table N1101.7.2(1) and then Table N1101.7.2(2).
INTERNATIONAL CLIMATE ZONE DEFINITIONS
MAJOR CLIMATE-TYPE DEFINITIONS
Marine (C) Definition—Locations meeting all four criteria:
  1. Mean temperature of coldest month between -3°C (27°F) and 18°C (65°F).
  2. Warmest month mean < 22°C (72°F).
  3. Not fewer than four months with mean temperatures over 10°C (50°F).
  4. Dry season in summer. The month with the heaviest precipitation in the cold season has not less than three times as much precipitation as the month with the least precipitation in the rest of the year. The cold season is October through March in the Northern Hemisphere and April through September in the Southern Hemisphere.
Dry (B) Definition—Locations meeting the following criteria:
Not marine and Pin < 0.44 × (TF - 19.5)[Pcm < 2.0 × (TC + 7) in SI units]
where:
Pin = Annual precipitation in inches (cm)
T = Annual mean temperature in °F (°C)
Moist (A) Definition—Locations that are not marine and not dry.
Warm-humid Definition—Moist (A) locations where either of the following wet-bulb temperature conditions shall occur during the warmest six consecutive months of the year:
  1. 67°F (19.4°C) or higher for 3,000 or more hours.
  2. 73°F (22.8°C) or higher for 1,500 or more hours.
For SI: °C = [(°F)-32]/1.8, 1 inch = 2.54 cm.
INTERNATIONAL CLIMATE ZONE DEFINITIONS
ZONE
NUMBER
THERMAL CRITERIA
IP UnitsSI Units
19000 < CDD50°F5000 < CDD10°C
26300 < CDD50°F ≤ 90003500 < CDD10°C ≤ 5000
3A and 3B4500 < CDD50°F ≤ 6300 AND HDD65°F ≤ 54002500 < CDD10°C ≤ 3500 AND HDD18°C ≤ 3000
4A and 4BCDD50°F ≤ 4500 AND HDD65°F ≤ 5400CDD10°C ≤ 2500 AND HDD18°C ≤ 3000
3CHDD65°F ≤ 3600HDD18°C ≤ 2000
4C3600 < HDD65°F ≤ 54002000 < HDD18°C ≤ 3000
55400 < HDD65°F ≤ 72003000 < HDD18°C ≤ 4000
67200 < HDD65°F ≤ 90004000 < HDD18°C ≤ 5000
79000 < HDD65°F ≤ 126005000 < HDD18°C ≤ 7000
812600 < HDD65°F7000 < HDD18°C
For SI: °C = [(°F)-32]/1.8.

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