It seems far-fetched to think of a gauge on your wall that can tell you when it’s a good time to hunt, but a barometer does exactly that. It measures the changing weight of air, or atmospheric pressure. Cold, dry air registers higher readings on the barometer than warm, wet air. So, large air masses of cold, dry air are called highs, and masses of warm, moist air are called lows. Highs, or high readings on the barometer, are associated with fair weather. Lows, or low readings on the barometer, are associated with stormy weather. Falling barometric pressure can indicate that a storm is coming in even before nice weather starts to turn nasty.
The activity of whitetails increases, making them more visible to hunters, with falling barometric pressure. Deer feel the change in pressure in their ears and other sensitive areas of their bodies. They have been conditioned, over the centuries, to read this change as a warning of an incoming storm. Their increased activity is associated with heavier feeding to fill their bellies before they are forced to take refuge from the stormy weather. So, when the barometer falls, start to hunt where whitetails like to eat.