In the United States, snake season is typically mid-March to mid-November. During the colder months of the year, pit vipers experience a form of hibernation called brumation. Brumation is an extreme slowing down of a snake’s metabolism. Rattlesnakes are awake, but just very lethargic so you don't see them moving around much. Rattlesnakes will usually search for underground dens during the winter to stay warm. Rattlers tend to form a hibernaculum, and pile into one spot that will have a fairly steady temperature throughout the winter. Oftentimes it’s a lava tube or cave. A hidden setting that typically holds at about 55 degrees is ideal for brumation. In populated areas, an unused basement in a house or an outbuilding can serve the same purpose. 
Although we know that rattlesnakes, copperheads, and cottonmouths are most commonly encountered from early spring through late fall, pit vipers are known to move around during extended warm periods even during the dead of winter. This is especially true if they hole up in a stump or other location that can be warmed easily by sunshine. On warmer days in winter, brumating rattlesnakes sometimes come out of their dens to bask in the sunshine. Nice sunny days that follow a long cold snap are often when people are surprised by rattlers. Just like humans, snakes head out to enjoy the sun and unsuspecting humans can startle them and cause them to strike. Better to be safe than sorry and wear snake gaiters (lower leg protection) when doing yardwork, cutting and stacking firewood, hunting, or hiking during warmer sunny winter days.
Of course it’s important to keep yourself safe when working or recreating in snake country, but also keep in mind that rattlesnakes aren’t inherently bad. They are natural predators of rodents, which can carry diseases and damage crops, so by controlling rodent populations, rattlesnakes help maintain a healthy and balanced ecosystem. Some of their venom even has medicinal potential for humans. Research into rattlesnake venom has led to the development of drugs for various conditions including cancer, pain, and heart problems. Other components of rattlesnake venom are being studied for their potential to treat a range of diseases such as Alzheimer's and Parkinson’s.
If you are bitten by a rattlesnake, seek immediate medical attention. Call 911 or get to the nearest hospital for anti-venom treatment. Don’t use a tourniquet or apply ice. Don’t cut the bite or try to remove the venom. Don’t drink caffeine or alcohol. Don’t take pain-relieving medicine, because doing so can increase your risk of bleeding. While survival from a rattlesnake bite without antivenom is probable, it's a serious and very painful medical emergency that can lead to severe complications and death if left untreated. Don’t take a chance! Seeking immediate medical attention is crucial for the best chance of recovery.
