Hunting Thermals: How Thermals Work for Whitetail and Elk

By Jake Roberts, retired Green Beret and founder of Wayward Ridge

I've been teaching hunters about thermals for years. For a long time I just talked it through, and plenty of people nodded along without really getting it. Once I started showing them what the air was actually doing on a piece of ground, it clicked for almost everyone.

This page is my attempt to do the same thing in writing. I'll walk you through what thermals are, how they change over the course of a day, and how I think about them over different forms of terrain. Whether you're hunting whitetail in the East or elk/sheep in the West, this knowledge is crucial to execution.

What are thermals in hunting?

Thermals are air moving uphill or downhill because the ground is warming up or cooling off. Warm air rises and cool air sinks. When the sun heats a slope, the air sitting on it warms and climbs. When that slope loses its heat, the air cools and slides downhill, a lot like water would.

Your scent goes wherever that air goes. I think of the wind forecast as the big picture for the whole area, and thermals as what's happening right on the slope you're sitting on. On a calm day, thermals usually decide where your scent ends up. When the wind picks up it pushes them around, but I rarely see it wipe them out completely. It's pretty common for the forecast to say northwest at 4 mph while the air in your draw is sliding straight downhill.

How thermals work, morning to evening

Before daylight. The ground has been giving off heat all night, so cool air drains downhill and settles into bottoms, draws and creek drainages. Whatever scent you leave walking in is headed downhill with it.

The morning switch. Rising air doesn't start at sunrise. It starts when the sun actually reaches the ground you're on and warms it up. East-facing slopes usually turn first. A shaded slope or a deep draw can hold falling air for hours after sunrise, and a cloudy morning slows everything down. While it's changing over, the air tends to swirl, and I'd rather not be sitting somewhere vulnerable when that's going on.

Midday. Sunny slopes push air uphill, and open ground gets going the strongest. Heavy timber warms slower, so it lags behind.

Evening. Once the sun leaves a slope, the ground cools and the air starts sinking again. Whichever side goes into shade first flips first. By dark, most of the ground is draining back toward the bottoms and the water, with another round of swirling during the change.

Shade and water. If there's a ridge to your east, your slope stays cold longer in the morning. A ridge to your west cools it off earlier in the evening. Creeks and rivers stay cooler than the ground around them day and night, so bottoms along moving water tend to pull air down toward them.

Thermals for whitetail: thermal hubs and setups

Thermal hubs. A thermal hub is a low spot where several draws or slopes come together. Air drains into it from more than one direction, piles up and swirls around. Mature deer like the ground around hubs because they can smell a lot from one place. If you walk into a hub, your scent goes everywhere, so I treat them as places to understand and stay out of.

Sitting low in the evening. Air falling off the ridges brings deer scent down to you. Your own scent is pooling in that bottom at the same time, and deer that come in late will often walk right into it. Before I sit low in the evening, I want to know where my scent is collecting and whether deer will cross it before I'm done.

Morning sits. Your scent drains downhill until the sun gets to your spot. I set up where that falling air takes it away from where I expect deer to be moving, and I want a rough idea of what time my spot is going to flip.

The walk in. You leave scent the whole way to your stand or blind, so I pick an access route where the falling air carries it away from bedding.

Height. Getting up higher helps some. Scent released at 20 feet travels differently than scent on the ground, but it still comes down somewhere.

Thermals for elk: climbing and dropping in the mountains

Elk country runs on the same pattern as whitetail country, just stronger. The relief is bigger and the temperature swings are bigger, so the air moves harder: down early, up once the sun hits, and down again in the evening.

The simplest way I know to put it is this. When the air is rising, stay above the elk. When it's sinking, stay below them. But, that's easier said than done. And you have to account for time when the thermals are switching.

Mornings. Air is draining downhill, so I'd come at them from below. Keep an eye on the time, though. Once sun hits that slope, your scent starts climbing toward them.

Midday. Elk often bed in cool, shaded timber where rising air lets them smell anything coming from below. That's usually when getting above them makes sense.

Evenings. The air drops again and your scent heads downhill. Come from below, or wait until the switch is finished.

Which way the slope faces. North-facing timber holds cool air. South faces switch early and hard. You can have rising air on one side of a drainage and falling air on the other at the same hour.

Calling. A bull circling downwind of your call is using the air to check you out. Think about where your scent will be when he gets there.

How to hunt thermals

1. 1.Start with the wind forecast, then think about what the air is doing on your slope.
2. 2.Figure out when your spot switches. That's when the sun reaches that ground, which can be well after sunrise.
3. 3.Plan your walk in with the same care as the sit itself.
4. 4.Stay out of your most sensitive spots while the air is changing over.
5. 5.Have a separate plan for mornings and evenings. The same property often needs different setups for each.
6. 6.Check it once you're there. A wind checker or a little milkweed will show you what the air is doing right then.

See thermals on your own ground

I built Thermal Lab Pro because seeing thermals is what made them make sense for the hunters I taught. You drop a pin on your ground, pick a day and hour, place your marker and watch where your scent goes.

It estimates rising and sinking air across your actual terrain minute by minute, using sun angle, shade, timber, cloud cover, moving water and wind. It's meant to sit alongside the mapping app you already use, not replace it.

$4.99/month or $29.99/year. 7 days free. Cancel anytime.

FAQ

Estimates only. Always confirm conditions in the field.