In METAR reports, what is indicated by a temperature of 0°C?

A temperature of 0°C in METAR reports indicates the freezing point of water. At this temperature, water transitions between its solid state (ice) and liquid state (water), which is a critical reference for pilots, meteorologists, and other professionals in aviation and weather monitoring. Knowing that the temperature is at the freezing point can be essential for assessing potential hazards, such as the risk of ice formation on runways or aircraft surfaces, which can affect safety and operational decisions.

While boiling point, icy conditions, and normal temperature may relate to various weather assessments, they do not accurately describe what 0°C signifies in the context of METAR reporting. The boiling point of water is 100°C at sea level, which is significantly higher than 0°C. Icy conditions generally imply that temperatures are consistently below freezing, but 0°C itself does not ensure that ice is present. Normal temperature can vary widely depending on the geographical location and time of year, further distinguishing it from the specific significance of 0°C as the freezing point.