Meditation under chilling conditions is still practiced in Japan. It is known as taki-shu-gyou 滝修行: meditation under chilling waterfalls. It is not only for experienced meditators, novice adolescents are also encouraged to take part: under "tiny waterfalls" (please check my previous post: Do you shiver?) Advocates are usually Zen-meditators. Tibetan practice of Vajrayāna Buddhism also features practicing under chilling conditions, quite common in Himalayan mountains. The practice of Tom-mo yoga of withstanding chilling conditions has been popularized in the West by famous iceman Wim Hof (who came to Hong Kong to demonstrate his practice some one year ago).
One may wonder why Taoist Neidan literature doesn't have such practices being mentioned. On the other hand, we do read accounts of Taoist Neidan practitioners who could withstand chilling weather and wore scantily during Winters (for example, Taoist Tan Qiao 譚峭 who wrote the famous "Tan's book-of-change 化書" was reported to wear scantily during Winter and wear heavily during Summer). The answer to this "riddle" is simple: Chinese have always been using cold showers during Winters as a way of training for good health and longevity (not to mention the fact that this method can save fuel, talking about Chinese pragmatism!). It simply doesn't need any special mention by spiritual or meditative practitioners to introduce the practice. Even these days, if one goes to the country side in Mainland China, one can still find many people of different age who will proudly tell you that they CAN take shower in Winter with chilling water!
The next question is: How to do training under a cold waterfall or shower? Or better put, the question is like: How NOT to shiver under a cold waterfall or shower?
Shivering is the body's self protecting mechanism of heat generation through involuntary muscle contractions. The gist of the "training secret" is before our muscles turn into full-blown shiver, they will subtly be "directed" by the meditative mind of the practitioner to be synchronized with one's chi-generator, one's lower Dantian (center of one's lower abdomen). The result is that the involuntary muscle contractions will be "sublimed" to drive up one's chi, which in its turn will "heat up" the body evenly. And such heating up can be controlled by one's focused mind.
The secret of all secrets in this practice is: to manage such sublimation at the "right moment". The window-of-opportunity after the body just begins to react with involuntary muscle contractions but before one gets into full-blown shivering. It is similar in concept to sexual sublimation in Neidan practice (check this post: The secret Taoist concept of "the right moment"). Improper sublimation, in the case of shivering, can result in catching a cold! And in the case of sexual sublimation....