What does the "Z" in the date/time group of a METAR or SPECI report indicate?

In a METAR or SPECI report, the "Z" in the date/time group signifies Coordinated Universal Time (UTC). This is the time standard commonly used in aviation and meteorology because it avoids the complexities of time zones and daylight saving time. Using UTC allows pilots and meteorologists to have a consistent reference point for data reporting and communication, which is crucial for safety and coordination in international aviation.

While local time and various standard times such as Eastern Daylight Time are important for operational contexts, they can vary significantly across regions and during different times of the year due to daylight saving adjustments. In contrast, UTC remains constant throughout the year, making it the ideal choice for global aviation operations.