What is the definition of a METAR?

A METAR is a type of aviation routine weather report specifically designed to provide real-time observations of weather conditions at an airport. It includes crucial information such as temperature, dew point, wind direction and speed, visibility, cloud cover, and other weather phenomena that can affect aviation operations. This standardized report format, updated typically every hour, is essential for pilots and air traffic controllers as it informs them about the current weather conditions they will encounter during takeoff, landing, and flight.

The other options mention summaries of weather trends, forecasts for seasonal patterns, and climate change impacts, which are not the primary purposes of a METAR. While useful in their own contexts, these types of reports do not provide the immediate, specific weather information required for aviation safety and operational planning.