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# * '''The 20 degree rule.''' A good approximation is to dress for temperatures that are 20 degrees Fahrenheit warmer than the actual temperature. So if it's 20 degrees out, dress for walking in 40 degrees. ## ** The faster your run, the more heat you generate, so the less insulation you need. The same temperature will feel different to different runners based on their height, weight and pace. ## ** This is a simplified rule, and the details depend on pace, height and weight; [[Perceived Temperature For Runners]] will give you a more accurate estimate. # * '''Don't sweat through.''' If you wear too many clothes and sweat too much, you will sweat through your clothes. Once your clothes are soaked, you will become suddenly chilled. # * '''Stay Cool'''. To avoid excessive sweating, you should aim to feel slightly cool, rather than comfortably warm. Don't get so cold that you shiver, but it's okay to feel chilly. # * '''Hydrate.''' Even in cold weather hydration is important. Use your thirst as a guide and for more on hydration see [[Practical Hydration]] and [[Hydration 101]].# * '''Numbness is bad.''' Your extremities may go numb early in your run, but they should warm up. Anything that stays numb needs to be checked as this can result in frostbite or other cold injuries. Beware anything that restricts circulation, such as elastic cuffs, as the reduced blood flow can contribute to frostbite.# * '''Watch for ice.''' Slipping on ice can pull muscles or cause falls. You can get traction aids to attach to your shoes if ice is a significant problem. See [[Traction Aids]] for more details. # * '''Emergency trash bag'''. If things go badly, a trash bag can help keep you warmer, especially if you have to stop running. You can fold a trash bag up quite small and tuck it in your waistband.

# * '''Adjust Your Clothing. '''It is of most importance that you adjust the amount of insulation you get from your clothing as the conditions change. Trying to make sure that your clothing is as flexible as possible.# * '''Zippers are your friend. '''And one of the best ways of adjusting the insulation you get from your clothing is to have zippers.''' '''Zippers on jackets and clothing allow you to quickly and adjust the amount of insulation to the conditions, and they can provide a fine grained adjustments.# * '''Dress in layers.''' Layers will keep you warmer than a single layer, and allow for flexibility of removing some of your insulation. # * '''Strip off after warm-up.''' If practical, you can overdress for the first mile or so, until you warm up. This requires you having somewhere to discard the extra clothes, or a way of carrying them. An alternative is to have clothing with zippers so you can reduce your insulation. # * '''Windproof layers are a mixed blessing'''. A windproof layer will boost the insulation value of the underlying layers, which can really help keep you warm. Unfortunately a windproof layer also stops sweat evaporating, which regulates your temperature. This makes it much more likely that you will sweat though and become cold. I use a windproof layer, but open it up as soon as I warm up, then try to stay slightly cool. A windproof layer is very useful as an extra layer, as it can be wrapped around your waist easily. I will wear it until I warm up, then carry it in case I need some extra warmth later in the run. # * '''Base layer'''. I recommend a close fitting, very thin base layer. The goal of this base layer is not to provide insulation, but to spread out the sweat, and prevent chafing. I typically run in an [[UnderArmour HeatGear Top]].# * '''Hat and gloves.''' These are important to keep you warm, but they can also be taken off and tucked in a waist band easily. This allows you to adjust your insulation for the conditions. # * '''Windproof underwear'''. For men, wearing underwear with a windproof front can provide vital protection. # * '''Protect the front'''. Wearing tights and top that are thicker and/or windproof on the front provide warmth while preventing overheating. The [http://www.golite.com/Mens-Black-Mountain-Thermal-Wind-Jacket-P46654.aspx Go Lite Black Mountain jacket] is excellent. # * '''No cotton.''' This is true for any conditions, but worth restating here. Wear clothes made from synthetic, wicking fibers, such as CoolMax. # * '''Wet insulation'''. Different materials can have very different characteristics when they are wet.## ** '''Insulation when soaked'''. Some materials are much warmer when they are completely soaked. Wool has a reputation of being one of the better materials for retaining warmth when wet. However any soaking wet material will cause you to lose heat through evaporation unless there is a windproof layer over the top.## ** '''Weight when soaked'''. I've found that some synthetic tops become surprisingly heavy when soaking wet. I don't know of any way of predicting this behavior other than trying it out.## ** '''Breathability. '''Some thermal layers will breathe well and allow sweat to evaporate before the government is soaked. This is good, as it allows your body to control its temperature through sweat affectively. Other materials do not breed so well and so the sweat will not evaporate until the government is completely soaked, at which point your temperature is likely to drop rapidly.# * '''Neck Warmer.''' A fleece neck warmer can protect your face and neck from the cold. I use a Turtle Fur neck warmer ([http://www.rei.com/product/663041 http://www.rei.com/product/663041]). # * '''Sunglasses.''' Keeping your eyes protected can help you keep a little warmer, and reduce how runny your nose gets. I use [http://www.amazon.com/Oakley-Half-Jacket-2-0-Sunglasses/dp/B007EN0FL0 Oakley Half Jacket sunglasses] with interchangeable lenses, so I can use clear glass when it's dark, or the cheaper and more convenient [http://www.amazon.com/Tifosi-Tyrant-Sunglasses-Gunmetal-Fototec/dp/B002Q1F1AA Tifosi Tyrant sunglasses] that have photochromic lenses that go nearly clear in dark conditions.

# * '''If your hands are cold, wear a hat.''' This is an old boy scout saying, but it works. If you core temperature starts to drop, your body will protect your vital functions by sacrificing your extremities, such as hands and feet. However, this is a delicate balancing act, as you need to stay cool enough that you are not sweating excessively.# * '''If your hands are cold, wear arm warmers.''' If you suffer from cold hands, then [[Arm Warmers]] may be the key. If your arms are cold, the blood flow to your hands is both chilled and restricted. # * '''Chemical Warmers'''. Using chemical warmers can help keep your hands from getting too cold. I find these seem to not only keep my hands warm, but also provide some extra warmth to the rest of my body and a little physiological boost. You can warm the packs with a hairdryer to get them extra warm (Thanks to Megan H). You can also save the hand warmers for another run by putting them in a sealed bag with the air squeezed out. (Thanks Charles/Kristine).# * '''Vaseline.''' If you are still having problems with your hands and feet, spreading Vaseline over them before putting on your socks or gloves will dramatically improve the insulation. It's a bit strange the first time you do it, but it works very well. # * '''Convertible Mittens'''. I've found that the gloves that include a cover to convert them into mittens work remarkably well. My favorites are the [http://www.amazon.com/Saucony-Womens-Ulti-Mitt-Large-Vizipro/dp/B006ZW6L4Q Saucony Ulti-Mitt].

# * '''Your lungs are fine.''' Your lungs will not freeze, not even at -40f/-40c. Your lungs may get irritated by the low humidity, but they will get used to that. (It is possible to get exercised induced asthma, which is a narrowing of the airways when exercising. If you suspect you have this condition, seek medical advice.)# * '''Suck then blow'''. If you have a problem with the tube on your hydration bladder freezing up, blow air back down the tube each time you have finished drinking. The drink is unlikely to freeze in the bladder itself, but the tube is very hard to keep warm. Insulation around the tube helps a bit, but not enough. (Thanks to Ron Bowman for this tip) # * '''Ski Goggles'''. Below -10f/-23c wear ski goggles or other eye protection to stop your eyelashes freezing together. Even in moderately cold conditions, eye protection can help keep you warmer and reduce the amount your nose runs. # * '''Cover gaps'''. Below 0f/-18c, it is critical to ensure there are no gaps or exposed skin. The phrase 'exposed skin freezes in minutes' should be taken seriously. # * '''Warm Up Inside'''. Often the first mile or so is the worst, as your body has not started to produce sufficient heat to offset the cold. Warming up for 10 minutes inside, by running up and down stairs, doing a jump rope, or using a [[Treadmill]]. (Thanks to Melanie M for this tip.) # * '''Start into the wind'''. If it's windy, start your run into the wind so that on the way back, you won't freeze due to sweating. (Thanks to Bobby A for this tip.)  

[[File:windchill.gif|framenone|thumb|500px|NOAA frostbite risk chart.]]