About this character
The degree sign is a small superscript circle used for three nearly unrelated measurements: temperature on the Celsius and Fahrenheit scales (23 °C, 72 °F), planar angles (90°), and geographic coordinates (40° 26′ 46″ N). The unit has a single shared graphical symbol but is parsed differently in each domain: in temperature contexts, the degree mark is followed by a unit letter (C, F, R, etc.); in angles, the degree is itself the unit; in coordinates, degrees combine with minutes (′) and seconds (″) of arc.
The Bidi class for U+00B0 is ET (European Terminator), which is how the Unicode Bidirectional Algorithm treats currency-like and unit-like trailing marks: they attach to a preceding number and inherit its directional context. In an Arabic or Hebrew paragraph, the sequence "23°" renders correctly with the degree sign hugging the number rather than floating into RTL text. See the bidirectional text guide for the rest of the algorithm.
Two glyphs are often confused with the degree sign. U+00BA º MASCULINE ORDINAL INDICATOR is the Spanish and Portuguese abbreviation for primero (1º) or doutor (Dr.º). It is taller, sometimes underlined, and is a letter (category Lo), not a symbol. U+2070 ⁰ SUPERSCRIPT ZERO looks similar but is a digit. For typed combinations like °C and °F, Unicode also provides the precomposed single-codepoint forms U+2103 ℃ DEGREE CELSIUS and U+2109 ℉ DEGREE FAHRENHEIT. These exist for legacy compatibility with East Asian character sets that included them; the SI and ISO 80000-1 style guides recommend using two-character ° + C/F rather than the precomposed forms. There is a non-breaking space (U+00A0) convention between the number and degree symbol in SI typography, and a thin space (U+2009) in some house styles.
From the Unicode data
Its East Asian Width is Ambiguous: it takes one column in Western contexts and two in East Asian legacy contexts, a common cause of misaligned tables in terminals.