What type of weather information is crucial for pilots during preflight preparation?

During preflight preparation, current atmospheric conditions are crucial for pilots because they provide real-time information about the weather that can directly impact the safety of the flight. This includes temperature, wind speed and direction, visibility, cloud cover, and any potential weather phenomena such as storms or turbulence. Understanding these factors allows pilots to make informed decisions regarding their flight plan, fuel requirements, and routing to avoid hazardous conditions.

In contrast, historical data of previous flights may offer insights into trends, but it does not reflect the current situation that a pilot will encounter. Information on nearby airports is also important, but it is only part of the broader picture that pilots need to assess before taking off. Forecasts for the next three days provide useful insights for planning longer trips, but they may not accurately represent immediate weather developments. Therefore, current atmospheric conditions are the most vital piece of information needed for safe and effective preflight preparation.