Keeping warm and dry on the run in the winter is really important. On a long run getting too cold will be mentally tough, slow your pace and potentially be dangerous if you have to stop as you can quickly become hypothermic. Winter running gear is different to, say, winter walking gear however as you produce a lot more heat and sweat when running.
Here are some tips on what to consider.
A Jacket; you can buy waterproof, windproof, shower proof, of a combination of those. Personally I have one good waterproof and windproof jacket and one lighter shower proof one. The British weather definitely requires the former! Look for Goretex for your waterproof jacket, I personally go for one without a hood as I’d never wear the hood up whilst running. I also like elastic cuffs for the wrists otherwise water runs down your forearms and pools around your elbows! Treat your jacket with care and follow the washing instructions when it needs it and it will last for ages. I use Tech Wash from NikWax to keep it waterproof. Personally I think this is the bit of winter running kit that it’s worth spending more on.
A hat; when it’s raining I love a peaked cap to keep the rain out of your eyes and face. On colder runs I go for a beanie hat, neither of my running hats are at all expensive. Whilst it’s not technically true that you low more heat from your head than elsewhere, your capillaries don’t constrict on your face and head, reducing blood flow there could be dangerous! Also you tend to have more skin on your face and head exposed, so keeping the head warm is important.
A buff; on colder days I also wear a buff around my neck, for the reasons stated above. But also when your neck and shoulders get cold you tend to lift your shoulder to your ears and huddle down into your coat, this changes the motion of your arms and your breathing when you run and will give you very sore shoulders and neck later.
Gloves; I have a cheap thin pair of running gloves that are perfect for most winter days. They have a small key pocket on one palm too, which is really handy. I also have a more expensive pair of sealskin waterproof gloves for really cold and wet days and they are wonderful, especially if you have a tendency to get cold hands!
Shoes; I’m usually out running in my usual running shoes over the winter. If it’s very wet I might consider wearing the pair of goretex off road shoes I own, especially if I’m heading out on the trails. These help keep mud, water and even droplets and dew off the grass away from your feet and therefore keep your feet warmer and dryer (less of a blister risk). On really wet days be aware that goretex shoes won’t drain as well, so once the water gets in they can get very squidgy! On trails I often run in small light gaiters, to stop mud, grit and stones from getting inside the shoes. Dirty Girl Gaiters are a great design and come in fab fabrics!
Socks; personally I run in the same socks all year round.If it’s wet I vaseline my feet before I go out to reduce the blister risk and reduce the wrinkling of the wet skin. But if you struggle with cold feet I would recommend Seal Skin waterproof socks, your shoes can get as wet as they like but your feet stay dry!!
Leggings; I always wear legging in the winter when I run, you can get thicker ones with soft brushed interiors which are fab on colder days. In the rain they get wet, but as your legs are working hard I’ve personally never had them get too cold in the UK.
Tops and Layers; A layering strategy is great for tops, a normal tshirt, a long sleeved layer and maybe also a warmer, thicker layer on top works well on the really cold days. You can then take off and add on layers as you need to. Merino works well for wicking sweat away from the body and being really warm but also lightweight. It’s not great when wet though. Maybe consider colour choice if it's going to be really muddy, the whites are never the same again...!
High Vis; if you are running after dark please wear a bright and reflective jacket, or you can get a cheap high vis tabard/vest to throw over the top. Mine is a Ron Hill one with a flashing LED light on the back for extra visibility on the dark roads and pavements.
If you are going out on a long run, especially when it’s on trails away from built up areas I always take a small running backpack with an extra warm layer with me. If I need to stop for any reason that will help keep me warm. If I don’t start out wearing my hat and gloves they go in the rucksack too. You never know when you might need them, just turning over on your ankle can leave you getting very cold very quickly.
Remember everyone is different, some people feel the cold more than others so the key is to try things out and have a few layers you can experiment with and swap around to create the best running outfit for different weather conditions and temperatures.