Fahrenheit - Usage

Usage

The Fahrenheit scale was the primary temperature standard for climatic, industrial and medical purposes in English-speaking countries until the 1960s. In the late 1960s and 1970s, the Celsius scale (known until 1948 as centigrade) replaced Fahrenheit in almost all countries, typically during their metrication process.

Fahrenheit is used in the United States, Belize, and the United States territories of Puerto Rico, Guam and the U.S. Virgin Islands for everyday applications. For example, U.S. weather forecasts, food cooking, and freezing temperatures are typically given in degrees Fahrenheit. Scientists, such as meteorologists, use Celsius or Kelvin in all countries. In some nations, both measures are quoted.

Various reasons have been suggested for the resistance to the Celsius system in the U.S., including the larger size of each degree Celsius (resulting in the need for decimals where integer Fahrenheit degrees were adequate for much non-technical work), the lower zero point in the Fahrenheit system (which reduces the number of negative signs when measurements such as weather data were averaged), and the more intuitive alignment of its 0-100 scale to the ordinary range of outdoor temperatures seen in most of the U.S. (e.g., 0°F = very cold winter day; 50°F = cool spring/autumn day; 100°F = very hot summer day; whereas 0°C = freezing (but not unusual) cold; 50°C = among the highest temperatures recorded on Earth, extremely intense, near-fatal heat; 100°C = unnatural, liquid water cannot exist).

Canada has passed legislation favouring the International System of Units, while also maintaining legal definitions for traditional Canadian imperial units. Canadian weather reports are conveyed using degrees Celsius with occasional reference to Fahrenheit especially for trans border broadcasts. Virtually all Canadian ovens make legal use of the Fahrenheit scale. Thermometers, both digital and analogue, sold in Canada usually employ both the Celsius and Fahrenheit scales. Also, in some instances, (swimming pool temperature or cooking temperatures in Québec for example), temperatures are still expressed in Fahrenheit.

Fahrenheit also remains in occasional use in the United Kingdom, with some newspaper and online weather reports quoting temperatures in both Celsius and Fahrenheit (or having an option to enable this), especially during record-breaking weather. However, TV weather reports are primarily conveyed using degrees Celsius. Cooking instructions on some (but not all) packaged food retain dual temperature scales for the benefit of consumers using older ovens, and dual-unit thermometers are readily available.