Hunting the Falling Thermal

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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 6:41 am

eric1986 wrote:
Divergent wrote:Thermals...Do you really understand the importance? Over the past few years of ground hunting I’ve been trying to perfect my sets. I’ve gained a lot of knowledge and boy have I made my fair share of mistakes. I’m starting this post because I feel like we need to expand on the thermal portion of the tactical thread. So, I’m hoping that this will be more of a conversation starter than anything. I will add some of my experiences as well.

I’m always reading about how to play the wind...hunting an off wind, wind in your face, wind just right for the buck etc. There are times when the wind plays an important role, but I strongly believe that a falling thermal is the single most important piece to a great setup.

How many times has a deer blown at you in late morning or early evening? I can only think of a couple of instances that I’ve been busted after the thermals were rising. I’ve seen them walk right by, never knowing I was in the area unless they crossed the path to my stand or natural blind.

Now, how many times has a doe or buck blown at you just at dark or at first light? I can name a million where I’ve been busted by a falling thermal. The air becomes more dense as the air temps cool and your scent becomes concentrated. This is especially important in the early season when you’ll see a huge swing in daytime highs and lows.

Your scent begins to pool up in certain topographical features once the sun starts to disappear behind the horizon. The greatest amount of deer movement comes around the rising and setting sun. Wind speeds will generally be lower at these times. This is why it’s so important to setup according to a falling thermal. Your setup for a 5-10mph NW wind during the day might be great for the three hours in early afternoon or late morning when the buck is in its bed. However, you might think otherwise when the thermals kick in and start pulling your scent back towards his exit trail at peak movement in evening or as he enters his bed on a j-hook trail in the morning.

The easiest way to understand a falling thermal is to follow the path from your location down to the lowest elevation. Imagine standing at your hunting spot, holding a water hose, and letting the water run for a solid hour. Where would it go? Is it going to cross a deer trail 20 yards away, leading from bed to food? Will it flow down a ditch, take a sharp right once it hits the main creek and flow down to a crossing 200 yards away?

When I setup on the ground I like to position myself below a trail or food source so my scent is pulled away from where I anticipate the deer to approach. I will also consider wind direction and where my scent might blow. This will help me decide which side of a draw I might setup on. I find that a perfect setup would be in a draw where the wind direction and the direction of draw both line up. This will keep the wind and thermals funneling up and down the draw.

There are certain times when I might tweak my sets. During the rut, I see a lot of early morning and then late morning movement. I typically see younger bucks move at daybreak trying to get first dibs on a doe. I would setup according to a falling thermal in these situations to avoid getting busted. Once the does make it back to bed I see more mature bucks start cruising for does. The does usually filter thru by 9-930am where I hunt. The thermals will have shifted by around this time. This is when I’ll move further up hill to catch him cruising. The other time is if it’s early season and I’m hunting a food source where a buck will drop down from his bed. On a calm day, you don’t want several hours of thermals to pull your scent up the hill to his bed. So, if there’s sufficient cover I’ll wait til a falling thermal and quickly setup for only the last hour or so of light to decrease my chances of him catching my scent.

In some cases your thermals might not matter very much at all. Thermals will have little effect with strong fronts with high winds.

I know there are far more knowledgeable hunters on here. So, please feel free to add anything to this thread.


This is a great post, and one I think most people dont consider as they should. I myself fall victim to this more often than I want to admit, especially looking for hot sign in new areas on 1st time sits. Thanks for starting this and getting so much intel to come in the following replies - its an overlook topic for most of the shows/podcasts.


I agree. You don’t hear about it nearly enough. There’s a podcast in the works though. We should be dropping it in about another week or so. My buddy’s MacBook but the dust, but he’s getting another one.


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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 6:47 am

d_rek wrote:Not hill country, but had falling thermals illustrated to me the other evening on a flat land / farmland hunt.

I sat a stand over a heavy trail used in a small finger of woods connecting two adjacent fields - one was thick pheasant habitat and the other was a recently cut bean field. The only tree I could sit was on the upwind side of the trail. I sat with the wind hitting me in the back for almost 2 hours, verified by watching milkweed blow directly onto trail and even out into adjacent field.

When the sun got to about the treeline the thermals started to drop and even though I could still feel wind at my back a little I watched the milk weed funnel to my left and out the opening of the trail that went to the field behind me, effectively taking my scent the opposite direction.

I did see deer (way out of range) but had one come in after the thermals dropped I think I could have gotten away with not getting scent busted. Unfortunately I think I may have mucked up my hunt in other ways (took the wrong access in, but that's a different conversation).


That’s the fine line you walk. Bucks are typically better about waiting for the switch. I’ve had does come out a touch early and screw things up before the thermals dropped.
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Re: Hunting the Falling Thermal

Unread postby Twenty Up » Thu Oct 11, 2018 6:49 am

Divergent wrote:
Twenty Up wrote:Something to add.. I’ve noticed after watching THP videos and their Public Land Challenge was how windy it gets in the Midwest. I’m an East coast guy, so this is merely speculation but I’m thinking our deer bed based more so off thermals than Midwestern deer. Not saying our deer don’t Bed wind to back, but they pick specific spots with microclimates and thermals/wind swirls that cater to them for low-no wind days. *

Take GA’s 10 Day weather forecast, even with a Hurricane hitting our highest wind speed is 18MPH but with an average around 5-7.

Madison Wisconsin’s 10 Day also hits 17 but has multiple double digit days bringing their average wind speed closer to 10-11

Just my speculation here but I’m really curious to hear other East Coast and Southern Beasts experiences and input on this.


I can tell you this for certain...Deer move more and spook less with moderate winds. Nothing is worse in my opinion that to have 10mph winds that drop to less than 5mph for the last hour of daylight.

The bedding still appears to be consistent with hill country bedding for me. I will say that they tend to drop in elevation for most of the summer. I think it’s because of the temps mostly. I find bedding to be more along the base of bluffs and along creeks and rivers in grasssy cover during the summer months. You might be onto something though. It could be because of the lack of wind...never actually thought about it. I just assumed it was temp related.


That too, your plans and wind usually go 180 on you real quick.. Or attempting to sneak within 100, 150 yards of a bedded buck on no wind days and dry conditions is like an act of Congress.

I’m noticing the bucks bedding low during summer months here as well, be it Hill country, rolling hills, farm it doesn’t matter. I’m noticing they’re still bedding like this now, the foliage cover and low 90’s temperatures are keeping them there is my guess.

My theory on them bedding low in creek bottoms or draws is the cooler air flows down and the warmer air on both sides pulls up, hits the top of the draw and drops down towards the buck. Allowing them to smell everything around them while looking down the draw “upwind”.

The first time I witnessed this the draw was setup in a “V” between two open fields. Both fields have sunlight hitting the ground, but inside the draw was shaded by oaks and significantly cooler. The very tip of the “V” was highest in elevation and also shaded by oaks.. So the warmer air from the fields was brought up to the tip, hitting the shade and beginning of the draw so the cooled air began dropping down to the bedded buck, which was looking downhill. This occurred on a low/no wind day with close to 100% humidity

That’s my take on them bedding down low anyways
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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 7:00 am

Twenty Up wrote:
Divergent wrote:
Twenty Up wrote:Something to add.. I’ve noticed after watching THP videos and their Public Land Challenge was how windy it gets in the Midwest. I’m an East coast guy, so this is merely speculation but I’m thinking our deer bed based more so off thermals than Midwestern deer. Not saying our deer don’t Bed wind to back, but they pick specific spots with microclimates and thermals/wind swirls that cater to them for low-no wind days. *

Take GA’s 10 Day weather forecast, even with a Hurricane hitting our highest wind speed is 18MPH but with an average around 5-7.

Madison Wisconsin’s 10 Day also hits 17 but has multiple double digit days bringing their average wind speed closer to 10-11

Just my speculation here but I’m really curious to hear other East Coast and Southern Beasts experiences and input on this.


I can tell you this for certain...Deer move more and spook less with moderate winds. Nothing is worse in my opinion that to have 10mph winds that drop to less than 5mph for the last hour of daylight.

The bedding still appears to be consistent with hill country bedding for me. I will say that they tend to drop in elevation for most of the summer. I think it’s because of the temps mostly. I find bedding to be more along the base of bluffs and along creeks and rivers in grasssy cover during the summer months. You might be onto something though. It could be because of the lack of wind...never actually thought about it. I just assumed it was temp related.


That too, your plans and wind usually go 180 on you real quick.. Or attempting to sneak within 100, 150 yards of a bedded buck on no wind days and dry conditions is like an act of Congress.

I’m noticing the bucks bedding low during summer months here as well, be it Hill country, rolling hills, farm it doesn’t matter. I’m noticing they’re still bedding like this now, the foliage cover and low 90’s temperatures are keeping them there is my guess.

My theory on them bedding low in creek bottoms or draws is the cooler air flows down and the warmer air on both sides pulls up, hits the top of the draw and drops down towards the buck. Allowing them to smell everything around them while looking down the draw “upwind”.

The first time I witnessed this the draw was setup in a “V” between two open fields. Both fields have sunlight hitting the ground, but inside the draw was shaded by oaks and significantly cooler. The very tip of the “V” was highest in elevation and also shaded by oaks.. So the warmer air from the fields was brought up to the tip, hitting the shade and beginning of the draw so the cooled air began dropping down to the bedded buck, which was looking downhill. This occurred on a low/no wind day with close to 100% humidity

That’s my take on them bedding down low anyways


That’s an interesting setup. Thanks for sharing. What state are you in Twenty Up?
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Re: Hunting the Falling Thermal

Unread postby d_rek » Thu Oct 11, 2018 7:40 am

Divergent wrote:
d_rek wrote:Not hill country, but had falling thermals illustrated to me the other evening on a flat land / farmland hunt.

I sat a stand over a heavy trail used in a small finger of woods connecting two adjacent fields - one was thick pheasant habitat and the other was a recently cut bean field. The only tree I could sit was on the upwind side of the trail. I sat with the wind hitting me in the back for almost 2 hours, verified by watching milkweed blow directly onto trail and even out into adjacent field.

When the sun got to about the treeline the thermals started to drop and even though I could still feel wind at my back a little I watched the milk weed funnel to my left and out the opening of the trail that went to the field behind me, effectively taking my scent the opposite direction.

I did see deer (way out of range) but had one come in after the thermals dropped I think I could have gotten away with not getting scent busted. Unfortunately I think I may have mucked up my hunt in other ways (took the wrong access in, but that's a different conversation).


That’s the fine line you walk. Bucks are typically better about waiting for the switch. I’ve had does come out a touch early and screw things up before the thermals dropped.


Yeah not the best setup i'll admit. I wasn't seeing the sign I expected to where I was, but was too far back to double back to a different area. Definitely learned a few things though.
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Re: Hunting the Falling Thermal

Unread postby whi52873 » Thu Oct 11, 2018 7:53 am

Divergent wrote:There are a few things that effect thermals that I haven't mentioned. Cloud cover can make the thermals get squirrelly if the wind speed is low enough. A passing cloud can cool an area just long enough to see the thermals balance out or fall, depending on the time of day.I find that a dense tree canopy can effect the thermals as well. You can find huge differences in just a few yards when you have field edges or select cut timber butting up to mature timber. I was hunting an area just last week on an out-of-state hunt in Georgia. It was a large field with a select cut, pine transition, that butted up against a dense mature canopy. If i was standing inside the dense canopy, my thermals were pulling South, down the draw into a bottom because the ground was cooler. If i was hunting in the select cut transition, I had no falling thermal advantage because the ground was still receiving some sun, so there was a slight thermal rise. This caused the "wind" to blow straight to the East and into the bedding area/exit trail. In the field on top, the "wind" was coming out of the south...which was a complete 180* change from inside the dense canopy that was shaded from the sun. If i were to setup outside of the dense canopy, i would've been busted if a deer came down the trail.

Cold creeks can have an effect on thermals too. I have areas that i can hunt in the middle of the day and have a falling thermal. These cold creeks seem to cool the surrounding air and there's a small pocket surrounding the creek that will have this falling thermal. Just 20 yards up the hill will have a rising thermal. You might also find that a particular side of the creek has more shade throughout the day or certain times of the day. Your thermals will change in these locations due to the ground cooling.


What is your experience on days you don't see the sun at all? For example, an overcast day, high is mid 50's, with a moderate wind. Should your hunting be strictly wind based and do thermals ever become a factor?
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Re: Hunting the Falling Thermal

Unread postby Twenty Up » Thu Oct 11, 2018 8:21 am

Divergent wrote:
Twenty Up wrote:
Divergent wrote:
Twenty Up wrote:Something to add.. I’ve noticed after watching THP videos and their Public Land Challenge was how windy it gets in the Midwest. I’m an East coast guy, so this is merely speculation but I’m thinking our deer bed based more so off thermals than Midwestern deer. Not saying our deer don’t Bed wind to back, but they pick specific spots with microclimates and thermals/wind swirls that cater to them for low-no wind days. *

Take GA’s 10 Day weather forecast, even with a Hurricane hitting our highest wind speed is 18MPH but with an average around 5-7.

Madison Wisconsin’s 10 Day also hits 17 but has multiple double digit days bringing their average wind speed closer to 10-11

Just my speculation here but I’m really curious to hear other East Coast and Southern Beasts experiences and input on this.


I can tell you this for certain...Deer move more and spook less with moderate winds. Nothing is worse in my opinion that to have 10mph winds that drop to less than 5mph for the last hour of daylight.

The bedding still appears to be consistent with hill country bedding for me. I will say that they tend to drop in elevation for most of the summer. I think it’s because of the temps mostly. I find bedding to be more along the base of bluffs and along creeks and rivers in grasssy cover during the summer months. You might be onto something though. It could be because of the lack of wind...never actually thought about it. I just assumed it was temp related.


That too, your plans and wind usually go 180 on you real quick.. Or attempting to sneak within 100, 150 yards of a bedded buck on no wind days and dry conditions is like an act of Congress.

I’m noticing the bucks bedding low during summer months here as well, be it Hill country, rolling hills, farm it doesn’t matter. I’m noticing they’re still bedding like this now, the foliage cover and low 90’s temperatures are keeping them there is my guess.

My theory on them bedding low in creek bottoms or draws is the cooler air flows down and the warmer air on both sides pulls up, hits the top of the draw and drops down towards the buck. Allowing them to smell everything around them while looking down the draw “upwind”.

The first time I witnessed this the draw was setup in a “V” between two open fields. Both fields have sunlight hitting the ground, but inside the draw was shaded by oaks and significantly cooler. The very tip of the “V” was highest in elevation and also shaded by oaks.. So the warmer air from the fields was brought up to the tip, hitting the shade and beginning of the draw so the cooled air began dropping down to the bedded buck, which was looking downhill. This occurred on a low/no wind day with close to 100% humidity

That’s my take on them bedding down low anyways


That’s an interesting setup. Thanks for sharing. What state are you in Twenty Up?


Georgia
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Re: Hunting the Falling Thermal

Unread postby Rich M » Thu Oct 11, 2018 10:29 am

I've been fighting with a response for this. I had asked a question about this a little while back and the answer was that thermals are as important, or more important as wind direction.

We need to factor for thermals - falling to rising or rising to falling in all out hunting and set-ups. In FL we basically get stillness at dusk and dawn.

In hunting FL, GA, SC over the past 3 years and have found ways to use the thermals to my advantage - hunting from over the top from the downside of a ridge, noticing that a seasonal ditch was a wind tunnel, and most recently, being able to use the falling thermals to keep my scent away from deer in the early AM, and then the rising thermal to do the same thing. These are my big realizations.

I'm no expert but learning that when the thermal and wind gets played right, we see a lot more deer up close and personal.

One of the neater wind things was the onshore/offshore breeze while hunting near Mosquito Lagoon in FL. Same thing as thermals, just a bit more solid of a breeze - maybe 10 mph-ish. Starts off gentle and steady in the am and then switched and grows in intensity.
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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 10:43 am

Rich M wrote:I've been fighting with a response for this. I had asked a question about this a little while back and the answer was that thermals are as important, or more important as wind direction.

We need to factor for thermals - falling to rising or rising to falling in all out hunting and set-ups. In FL we basically get stillness at dusk and dawn.

In hunting FL, GA, SC over the past 3 years and have found ways to use the thermals to my advantage - hunting from over the top from the downside of a ridge, noticing that a seasonal ditch was a wind tunnel, and most recently, being able to use the falling thermals to keep my scent away from deer in the early AM, and then the rising thermal to do the same thing. These are my big realizations.

I'm no expert but learning that when the thermal and wind gets played right, we see a lot more deer up close and personal.

One of the neater wind things was the onshore/offshore breeze while hunting near Mosquito Lagoon in FL. Same thing as thermals, just a bit more solid of a breeze - maybe 10 mph-ish. Starts off gentle and steady in the am and then switched and grows in intensity.


This is the same thing I see in Alabama too. Those ditches are killer. You almost always know where the bucks will cut across the ditch too. They’ll usually throw a rub in the middle or on the edge of it where they cross. I setup on either the up or down side depending on the time of day. Early morning and late evening I walk down the middle of the ditch and setup low, facing uphill. In the middle of the day I’ll setup above the crossing. If there’s a stiff wind, I might stay below on the downwind side because it’s overriding the thermals.
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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 10:57 am

Ok, so I’m doing all of these diagrams from my phone, so please forgive me if I’ve made any mistakes or if it’s a jumbled mess.

This is what it looks like when I arrive. Wind out of W/NW. Thermals are funneling up each of the hillsides. Deer are bedded wind to back, overlooking hardwood bottom. This is early season and there’s plenty of green foliage. The creek is especially thick. Red dots are possible bedding locations...although I’m only focusing on the beds to the far left.
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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 11:01 am

My access and pre falling thermal setup in green
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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 11:05 am

Sun is starting to set to the west. The first bit of shade is cast on the east facing slope. The thermals start to drop. The west facing slope is still in the sun. The thermals are still rising. Image
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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 11:15 am

Once there bedding starts receiving shade I move to the lower elevation. The sign in the bottom will tell you where the thermal hub is located. You’ll see rubs and possibly scrapes where they drop and go up an opposite ridge.
You can see small red dots. These mark travel route of deer dropping.
Orange is most likely where you’ll find the sign. They can check the ridges and draws to the south from the southern orange dot. They can check the southern and northwestern draws/ridges from the top orange dot.
You do not want to be setup higher in elevation than whichever hub location they’re using. If you are higher in elevation you will likely get busted by the falling thermal. You want to setup lower in elevation, so your scent is carried away from the sign. Image
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Re: Hunting the Falling Thermal

Unread postby Tempy » Thu Oct 11, 2018 1:41 pm

This thread is incredible.

So divergent, what time of year do you see these hubs being most beneficial to hunt? Pre-rut I'm assuming? And when do you scout for sign to see if the hub is active prior to hunting the area?

Also, can you describe a converging hub and how you would possible setup with rising thermals?
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Re: Hunting the Falling Thermal

Unread postby Divergent » Thu Oct 11, 2018 2:27 pm

Tempy wrote:This thread is incredible.

So divergent, what time of year do you see these hubs being most beneficial to hunt? Pre-rut I'm assuming? And when do you scout for sign to see if the hub is active prior to hunting the area?

Also, can you describe a converging hub and how you would possible setup with rising thermals?


The early it is, the better in my opinion. Once the leaves drop, they’re not going to move as far in daylight and it’s difficult to get into place without being seen. I would say the prerut is the best time. The rut in my wma is full swing around thanksgiving. Starting around October 15th there’s a 10 day period I see rubs and scrapes pop up. There’s a lull til November 15th and then there’s another week of rubs and scrapes. I would target them during this time. So, if you know your area well then you probably know when to hit them up. I think some of the Midwest probably sees this starting as early as around the end of September.
There are certain spines that shoot out in different directions with the converging hubs. The rising thermals meet up in a central location. I’ve seen the deer place scrapes and rubs near the tops. I ran into a buck using an area like this years ago, but it’s not something I really focus on anymore. I shifted my focus to long ridges where there’s multiple beds on secondary points. This is where all of my late morning setups are now. I hunt a perpendicular trail cutting above or below the doe beds depending on where I run across the rubs in ditches. This tells me which one they’re using.


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