The state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. :)
A 270 Weathery will shoot any standard 270 bullet. However a Weatehrby Magnum will not. The Weatheby Magnum is like a Winchester Magnum which is a shorter and fatter cartridge.
You can typically find historical high and low barometric pressure readings for yesterday in weather records from meteorological stations, online weather databases, or through weather tracking applications and websites. They usually provide daily weather summaries that include barometric pressure data.