Weather means the atmospheric conditions, including wind, temperature and precipitation, in a specific area at a specific time.
Weather refers to atmospheric conditions such as wind, temperature, and precipitation, all of which have a large influence over aviation activities, especially flights. Weather is a key factor in flight-planning, but also affects aircraft-design and equipment, and is always included in flight-training.
National weather services usually prepare aviation-specific forecasts and other information, and there are international formats for describing weather in aviation terms. Among the most well known are metars and tafs, which are current observations and forecasts for a specific airport or weather observation point.
This tag is appropriate for all questions where weather is a factor, including weather observation and forecasting (for aviation specifically), the effect of weather on aircraft and flight planning, in-flight operational considerations, etc..