Celsius Celsius The Celsius scale, also known as the centigrade scale, is a temperature scale used by the International System of Units (SI). As an SI derived unit, it is used by all countries except the United States, the Bahamas, Belize, the Cayman Islands and Liberia. It is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale. The degree Celsius (°C) can refer to a specific temperature on the Celsius scale or a unit to indicate a difference between two temperatures or an uncertainty. Before being renamed to honor Anders Celsius in 1948, the unit was
Celsius formally adopted "degree Celsius" in 1948, formally keeping the recognized degree symbol, rather than adopting the gradian/centesimal degree symbol. For scientific use, "Celsius" is the term usually used, with "centigrade" remaining in common but decreasing use, especially in informal contexts in English-speaking countries. It was not until February 1985 that the weather forecasts issued by the BBC switched from "centigrade" to "Celsius". Some key temperatures relating the Celsius scale to other temperature scales are shown in the table below. The "degree Celsius" has been the only SI unit whose full unit name contains an uppercase letter since the SI base