How did medieval people keep warm? The short answer might be they didn’t, but that’s only half an answer. Certainly, in medieval Wales like in modern Wales, people didn’t have to deal with extreme temperatures of say–Minnesota–but they did have to deal with snow and cold in the winter, and occasional heat waves in the summer.
How did they protect themselves against the cold? Houses, certainly, weren’t kept very warm. Cloaks, scarves, boots, and gloves were worn indoors. Especially with the inefficient and smoky heating system (see my post on chimneys), the cold inside could approximate the cold inside.
Medieval people had gloves, for example: http://medievalgloves.blogspot.com/2007/11/three-pairs-of-gloves.html
“For the peasant, the garb was basic and simple. The outer clothing was commonly made of wool with undergarments of linen. As one would expect, the wool garments were hot, heavy and itchy, but fortunately, the linen undergarments made the wool a bit more comfortable. The undergarments were laundered, but it was rare to wash the outer garments. While one might think this would serve to create a rather pungent society, such was not necessarily the case. Though the peasants worked very hard, frequently at manual labor, they also spent a great deal of time around open fires and smoke. The smoke permeated their clothes and acted as a natural deodorant reducing the odors.
In the winter and colder months, cloaks, mittens and woolen hats were worn as protection from the elements. Shoes were worn, but were often a luxury. Leather boots could be found among the peasants, but it was not uncommon for peasants to go without shoes. Along with their woolen dresses, women often wore simple caps.” http://www.medieval-period.com/medievalclothing.html
BBC did a feature on what Robin Hood might have worn in Sherwood Forest to keep warm in winter: “In the medieval era, clothes would be made of wool with a next-to-body material generally of linen. Both materials – worn in layers – are excellent to keep you warm. Perspiration reduces this effectiveness, so if you couldn’t avoid sweating for some reason and you became hot through physical exertion the correct thing to do would be to take a layer or two off until you cooled down, then put the layers back on again.
Medieval men wore a linen shirt and underclothes, a woollen coat with a hood over a coif – a tight fitting cap – on the head and also covering the shoulders and upper arms. Gloves were known – by comparison to our modern five-fingered gloves medieval winter gloves had two ‘fingers and a thumb’ only or more likely looked like mittens, made from wool or padded / lined leather.
Even soaking wet wool provides a modicum of warmth. Our medieval outlaws couldn’t wear anything else anyway, as fibres such as polyester, lycra and nylon weren’t invented and silk was both rare and too expensive for a common man when seen at market (Silk is a recommended next-to-body material for keeping warm, but rare in England for many years to come. Being an outlaw, if you couldn’t afford any silk you could always steal some).
Wool if clean and maintained is waterproof up to a point, but would not resist a downpour and shelter have to be sought. Wool can be waterproofed, but this affects the warmth it provides.
A far better and a more common waterproof for wintertime would be leather – a fatty skin taken from an animal such as a deer or a pig or a skin treated and tanned into leather and fashioned into a cloak, perhaps including a hood.” http://www.bbc.co.uk/nottingham/features/2003/12/sherwood_forest_survival_guide.shtml