Soldier’s Handbook for Individual Operations and Survival in Cold-Weather Areas TC 21-3 Full Size There are different types of cold found throughout the world and each presents its own challenges. For Soldiers to be effective in a cold-weather environment, it is essential they first understand the effects of cold on the body and equipment. (See ATP 3-90.97 for more information.) Weather is considered to be cold when the temperature registers 39 degrees (°) Fahrenheit (F) or 4° Celsius (C) above (+) zero and drops to negative (–) 40°F or lower. The Army groups cold temperatures into five categories: • Temperature zone I (wet cold): +39°F to + 20°F (4°C to –7°C). • Temperature zone II (dry cold): +19°F to –4°F (–7°C to –20°C). • Temperature zone III (intense cold): –5°F to –25°F (–20°C to –32°C). • Temperature zone IV (extreme cold): –25°F to –40°F (–32°C to –40°C). • Temperature zone V (hazardous cold): –40°F (–40°C) and below. Intense cold exists from –5°F to –25°F (–20°C to –32°C) and can affect the mind as much as the body. Intense cold has a rapidly numbing effect. Simple tasks take longer and require more effort than when done in warmer temperatures. The quality of work degrades as attention to detail diminishes in this type of environment. Clothing becomes bulkier to compensate for the cold, causing Soldiers to lose dexterity. Commanders need to consider these factors when planning operations and assigning tasks. Extreme conditions occur when the temperature falls below –25°F (–32°C), and the challenge of survival becomes paramount. During extremely cold conditions, individuals can easily prioritize physical comfort above all else. Soldiers may withdraw into themselves and adopt a cocoon-like existence. Leaders should expect and plan for weapon, vehicle, and munition failures when temperatures drop this low. Leadership, training, and specialized equipment are critical for successful operations in this harsh environment. During hazardous conditions, commanders and planners assume a great deal of risk if they choose to engage in operations when the temperature falls below –40°F (–40°C). Extensive training is required before undertaking an operation in such extreme cold. W IND C HILL Wind chill is a measure of the combined effects of wind and temperature. Temperature alone does not give a true indication of the impact of cold weather. To effectively gauge the difference between temperature and the impact of cold, a wind-chill scale is used. A simple and practical guide outlining the conditions when cold weather becomes dangerous and exposed flesh is likely to freeze can be found in chapter 4 of this publication. Familiarity with the included wind-chill chart helps Soldiers recognize these dangers.