Winters in India can take many people with surprise. This does not happen only in the case of inbound foreign travelers but to Indians as well. One of my acquaintance traveling to Madhya Pradesh without any warm clothing, shivered throughout his journey from Nagpur to Jabalpur.He made it alive.
We were caught unawares plenty of time in higher reaches of Nainital by heavy snow. It can snow at Sat Tal and Pangot anytime as late as April. Hence in all my birding expeditions I keep plenty of warm clothes. These are required in summers as well although thinly as it could be very chilly during the predawn in many places in India.
The cold begins in India from October onwards and keeps to North and Central India but it can surprise people even in Mumbai which was much colder last year than it used to be. Warm cloth suppliers did brisk business at that time.
The Himalayan Reaches receive continuous snow and cold blasts of wind. Kashmir is very cold during winters and whence blasts of cold wind strike Uttar Pradesh, Rajasthan and Madhya Pradesh shiver. Punjab, Haryana and Himachal Pradesh experience record breaking cold though the former two do not experience snowfall. Similarly it does not snow in MP and Uttar Pradesh but the shivering cold persists till January.
Whence traveling in India be prepared with lots of warm clothing including hand gloves and head gear. Do not take chances there is very little conditioning in public places including restaurants. The cold waivers between less cold and more cold but it remains right till January and sometime stretches till February in extreme form. There are very good quality warm garments being sold in areas with cold hence do not hesitate to buy them if you do not have. In extreme cold warm inner are a must, buy the branded ones they are generally protective against extremes.
Hot tea is like manna during winters and it is safe as well. Keep sipping keep some brandy it helps if badly struck. The common sense advice is to restrict travel to day time nights can be Freeeeeeeeeeeeeezing! Burr!