Understanding Weather, Moon Phase, and Deer Activity

Understanding the combination of weather and moon phases on deer movements can help hunters bring more venison home instead of eating your tag. The question becomes: Although solunar tables, magazine articles, internet searches, and apps are informative when it comes to predicting deer movements, are any of these based on science?

Hunters are always looking for shortcuts to maximize their time in the stand. Years ago, my one-stop source for information on deer movements was my Pap. I still vividly recall him randomly pulling me out of school and saying, “We have to hit the woods. The weatherman is calling for a cold front tomorrow. The deer will be out feeding this afternoon.” Although getting out of school was great, I’ve learned that cold fronts have nothing to do with predicting deer movements. Yet, many hunters swear by this strategy. If you’re one of them, I’d love to review your data, because scientific data proves otherwise.

Biologists know that weather is made up of multiple parameters including air temperature, atmospheric (barometric) pressure, humidity, precipitation (rain, sleet, snow), visibility, cloud cover and cloud type, solar radiation, and wind (speed and direction). Combinations of these parameters can cause a cold front, warm front, stationary front, and an occluded front, which is when a warm air mass gets caught between two cold air masses.

Combine these weather conditions with the four phases of the moon (full, waxing, new, waning), and it gets complicated. As you know, all of these moon phases can give off different amounts of moonlight, depending on the weather conditions. Additionally, an October full moon could be 100,000 miles away from the Earth at a 40-degree angle. The following November’s full moon could be 200,000 miles away at a 270-degree angle. Remember, all moons are not created equal. This is one reason why comparing one moon to the next is like comparing apples to oranges.

Biologists have studied and measured each of these aforementioned factors independently, and in combination with each other, to determine the best deer movements. How did they accomplish this? Today, biologists radio collar deer and use cellular technology to record hundreds of thousands of deer-movement data points. All this data is then statistically associated with the various weather parameters and moon phases.

Study after study has been consistent: Data has not indicated any significant pattern to the effects of moon phase or weather parameters on buck or doe movements. Various studies have also subdivided this data to daytime versus nighttime movements during the hunting season. The result was still the same: The weather and moon had no significant effect on deer movements during either the day or night.

Hunters must remember that deer do two things during the fall hunting season — feed and breed. A deer must fill its belly, no matter what the weather is doing. But, if there’s one weather parameter various biologists have noted that most likely affects deer movements, it’s significant changes in barometric pressure. For example, a rapidly falling barometer associated with an extreme weather change or storm event such as hurricanes. These examples can have a positive effect on daytime deer activity.

But chances are, you’re not going to believe any of this peer-reviewed scientific data if you shot a 200-inch buck under a full moon, with 30 percent barometric pressure and a pending cold front coming. Obviously, I can’t blame you. But can site-specific or localized weather and moon parameters correlate to increased deer movements in your area? Maybe, but I’m willing to bet these highly localized movement patterns are just that: very specific to your area, and inconsistent from one year to the next.

One area of research that still needs to be analyzed is looking at the effects of various weather parameters with a time lag (for example, minus one day). In other words, compare daytime buck movements to the previous day’s barometric pressure. My assumption is during inclement weather, deer will not feed as much as they regularly do. Thus, the following day deer will try to make up for the previous day’s limited diet. But who knows, because science has not analyzed this data. I have personally found this to be more consistent than purposefully hunting the day before any inclement weather. Either way, the best time to hunt is when you have time to hunt, regardless of the weather or moon phase.

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If you’re having trouble finding deer and blame it on the moon or weather, you may want to move your stand to a more desirable food location. Why? Because deer are slaves to their belly and are most likely eating their groceries somewhere else.

Although some hunters may still question this research, these are some of the weather generalizations that are interesting: (1) Some authors state that severe winter storms with high winds and low temperatures will decrease deer activity. (2) As wind speed increases during the winter, deer move to habitats that support heavy cover or provide a wind-screen effect. (3) Deer activity will decrease during colder temperatures and increase during the daytime. (4) On cold days during the winter, deer became more active as skies cleared, and deer increased their use of open habitats, taking advantage of solar radiation in order to feed in otherwise unfavorable temperatures. (5) Although some hunters believe deer activity is keyed to changes in relative humidity, the data is contradictory. Previous studies have determined both increases and decreases in deer activity. (6) Cloud cover does not appear to influence deer activity or habitat use in any season. On cold days during the winter, deer became more active as skies cleared and increased their use of open habitats, apparently taking advantage of solar radiation in order to feed in otherwise unfavorable temperatures.

C.J.’s Summary: After almost four decades of hunting and studying deer from a biologist’s perspective, I’ve learned one thing: Just when you think you’ve solved deer-movement patterns by associating them with weather or moon parameters, you’ll be humbled. Although biologists and hunters are always trying to piece together buck movements in relationship to moon phase and weather parameters, no data has been found to completely solve the puzzle.

I’ve seen data that show changes in barometric pressure does and/or doesn’t affect deer movements. But again, what you experience in your hunting locale may be different. Although writers may claim moon phase and specific weather parameters influence deer activity, no one has the magic pill for animal magnetism or accurately predicting deer movements. The bottom line is this: From a scientific standpoint, there are too many variables to consistently sort out deer activity in relationship to moon phase and weather.