Animals use the wind to detect different scents in the air. Many animals, especially deer, trust their sense of smell over all other senses. With smell being their number one defense in avoiding danger, understanding wind patterns in your area to avoid being scented can make or break a hunt. A few wind terms you will hear repeatedly in regards to hunting are upwind, downwind, prevailing wind, swirling wind and thermals. The breakdown of these terms should help establish basic knowledge to start understanding your local winds.
Most stories that involve a hunter being upwind of their game ends with the hunter going home empty handed. If you are upwind, it means that the wind is blowing from you to the animal. A deers sense of smell can pick up the slightest amount of human scent, so every effort should be put toward avoiding being upwind of your quarry.
Being downwind of something means the wind is blowing from the animal to you. Constantly checking the wind to ensure your scent is blowing away from where you expect deer to be is essential. Tree stands and blinds should always be placed downwind of where you anticipate your game to be. It is equally important to remain downwind of deer while entering and remaining downwind of bedding areas during while entering and exiting your hunting location is equally important as being downwind of your target while actively hunting.
Prevailing wind is the most common direction the wind blows in your area. Generally, the jet stream establishes prevailing winds. Knowing which direction the prevailing winds come from help you in choosing tree stand locations and entry and exit strategies. While high and low pressure fronts can create all different wind directions, if one has a W wind 5 out of 7 days a week that would be your prevailing wind.
In hilly or mountainous terrain, wind also follows thermals. Thermals are an effect due to temperature change. As the air warms with the morning sun, the heat will rise and essentially push a wind draft uphill. As the air starts to cool in the evening, the cool air will sink and wind will draft downhill. A good way to remember this is that heat rises and cold sinks, so as the temperature rises and falls the wind goes with it.
Swirling winds are simply that. Winds that swirl around rather then blowing steady in one general direction. Swirling winds are probably responsible for more blown opportunities on game than anything else. Scent prevention is extremely important in swirling winds.
There are many ways to detect wind direction from electronic devices to simply releasing something light, like down feathers or putting a puff of non scented powder in the air. When deciding on a hunting location, wind can often be checked right from home by watching your local weather channel or viewing local weather on your phone. When a local weather forecast states that you will have a N-NE wind for example, that means the wind will be coming from North or Northeast and heading South or Southwest. If the forecast predicts a W wind then the wind will be coming from the West and heading East.
Forecasted wind directions from local newscasts and weather channels are great for giving general wind direction, but wind can be adverted by many small land features and objects. A good way to envision how wind will flow through a landscape is to picture how water flows down a river. The way water flows around a rock and swirls on the downstream side is very similar to what wind will do when it flows over ridges, through draws and around any other abrupt changes in the topography. Understanding local wind patterns and using them to your advantage to avoid scent detection is an extremely important tool, regardless of what and where you hunt.
Keep the wind in your face and success will smile upon you!