What does a negative temperature value represent in METAR?

A negative temperature value in METAR indicates freezing temperatures. In aviation and meteorology, temperature values are often reported in degrees Celsius. When a temperature is given as a negative number, it signifies that the air temperature is below 0 degrees Celsius, which means that conditions could facilitate the formation of ice on airfields, aircraft, and other exposed surfaces. This is particularly important for pilots and ground crews, as freezing temperatures can have significant implications for aircraft performance and safety. In contrast, the other options, such as heat wave conditions, overheating, or mild weather, do not accurately describe the effects or implications of negative temperatures in METAR reports.