September 27, 2023
We'd stalked as close as possible to the big prong- horn buck. He was getting nervous, and we were out of cover. The distance was 440 yards—exactly a quarter mile. Doable in calm conditions, but a cross-wind was gusting. Uncomfortable with the shot, I lay in the sparce, sun-dried grass and watched the conditions. I had the right rifle, cartridge, and bullet; a super-accurate custom 6.5-284 loaded with a streamlined Nosler AccuBond. Finally, prone and steady, I held the crosshair about nine inches into the wind and squeezed the trigger.
Impact was too far back. I’d underestimated the wind drift by half. Running the bolt fast, I compensated accordingly and finished the buck.
Thankful I’d managed to rectify my mistake quickly; I began running through what went wrong. Clearly, my read on the strength of the wind was off. Plus, the wind was gusting, which made it much harder to predict. And exacerbating the issue, there were very few good environmental indicators (tall grass, tree leaves, floating bugs) of the wind’s strength. In retrospect, I shouldn’t have taken the shot.
That was a long time ago. In the years since, I’ve learned more patience, and my willingness to risk a challenging shot in unpredictable wind conditions has decreased. I’ve also learned a few things about reading wind more effectively.
Long-range shooters use the term “value” to describe how much affect the wind has on a shot. A full-value wind is a 90-degree wind. It blows perpendicular to the path of the bullet and has maximum effect. A no-value wind is either straight behind or straight into the nose of the bullet. As the term suggests, this has no lateral affect on bullet flight.
Shooters call wind by the clock. Imagine the marksman is the center of a clock face. Straight ahead is 12 o’clock, straight behind is 6 o’clock.You get the drift, no pun intended.
Full value winds are from 3 and 9 o’clock. For practical purposes, I consider anything from about 8:30 to 9:30 and from about 2:30 to 3:30 full value, and anything from 11:30 to 12:30 and from 5:30 to 6:30 to be no-value wind. It’s the ’tween values that are perplexing. A rule of thumb is to accord 75 percent of full value to oblique winds. At this point in the game, correctly calling wind is more art than science.
Obviously, the faster the wind, the more your bullet will drift. If you use a device such as a Kestrel (see sidebar) to get a precise read on wind speed and value, it’s relatively easy to compensate quite accurately. That is, if the wind is consistent all the way downrange to the target.
In hunting country, it rarely is. Desert draws and mountain canyons suck the breeze this way and that. Undulations in the earth cause thermal drafts. Even cloud shadows scudding across the ground influence the direction and strength of the wind.
As a result, there are often multiple wind vectors between you and your quarry. No device can read wind speed direction and strength several hundred yards away. It’s up to you to look over the lay of the land, to watch environmental indicators between you and the target, and to make the best wind-compensation call you can.
Watch for movement in grass, particularly tall grass. Watch for tree leaves to shiver. Look for dust stirring. Look for cottonwood fluff or insect swarms hanging on the breeze. If wind is strong enough to sway small trees, take note. Look for these indicators at your shooting position, around your quarry, and in-between.
Most important is right at your shooting position. Wind right at the target has little time to work on your bullet. At your shooting position, it will push your bullet just slightly off course as well—but that new vector magnifies with distance.
Some rules of thumb for estimating wind by environmental indicators: A gentle breeze on your cheek is 3-5 mph. Leaves shiver at 5-8 mph. Dust stirs and raises at 8-12 mph. Trees sway at 12-15 mph.
READING MIRAGE TO ESTIMATE WIND
Spotting scopes and high-magnification riflescopes with parallax adjustment are very useful for reading wind strength by looking at heat waves—or mirage— coming off the earth.
To read mirage, focus on your target, then bring the focus back toward you. Mirage between shooter and target becomes visible.
If mirage rises straight up, or“boils,”there’s no need to hold for wind. If it tips 60 degrees, wind is 1-3 mph. When mirage tips 45 degrees or thereabouts, wind is 4-7 mph. If mirage blows so low and fast it appears parallel to the earth, wind is 8-12 mph. Faster than that, you’ll usually just see dust in the scope—no mirage—and you shouldn’t attempt extended-range shots at game.
The cool thing is, when your scope is pointed in a given direction, mirage provides the effective wind speed you need at that vector, not the actual wind speed. For example, if you’re shooting in a 10-mph wind but it’s straight behind you, the mirage will appear to boil in the scope, indicating a no-value shot.
For those of us that hunt the wide-open West, cross-can- yon shots are common. And problematic. It’s usually impossible to estimate wind between you and the target because there are no environmental indicators, and so far above the earth, there is no mirage.
Here’s what I do: After estimating the wind strength at my position and in the bottom of the canyon, I average the two, then double it. Experience has shown me that air flow well above the ground, being free of friction with trees and shrubs and such, is much faster than near the ground.
PRACTICE MAKES PERFECT
Well, hardly. Nobody is perfect at reading and compensating for wind. But practice does make you much more proficient.
With today’s modern ballistic calculators, we can compensate precisely for bullet drop. No matter the altitude, temperature, barometric pressure, or angle, space-age tools crunch the input and regurgitate accurate solutions. Even the effect of the rotation of the earth on bullet flight can be precisely calculated.
Not so with the wind. Pure marksmanship is the only thing that successfully compensates for wind. Commit methods to memory. Polish skills afield. You’ll be a better hunter for it and won’t be likely to make the mistakes I did on that big pronghorn buck.