What is required for an alternate airport in relation to weather at the time of arrival?

For an alternate airport, having weather reporting capabilities is essential because pilots need accurate and current weather information to make informed decisions about their approach and landing. The alternate airport serves as a backup option in case the primary airport becomes unsuitable for landing due to deteriorating weather conditions. Therefore, the alternate airport must provide reliable weather data at the time of arrival to assess its viability for landing. This ensures that the crew can evaluate whether it is safe to divert there, based on the actual weather conditions at that location.

While other factors such as proximity and air traffic control approval may be relevant in selecting an alternate airport, the most critical requirement is the availability of accurate weather reporting. This information directly influences safety and operational decisions, making it a pivotal aspect in flight planning.