The winter season in Pakistan is very pleasant except on the mountains where the winters are very cold.
Pakistan has a short and mild winter which starts about the middle of November and ends about middle of February. On the plain stations like Lahore, it is one of the best season of the year. The highs are in low 70s and the lows in 40s. The sky is clear, the sun bright and bracing. The rainfall is low and the season as a whole is dry. It is the best time of the year to travel any where except towards the mountains.
The mountains to the North have a long and harsh winter. Skardu, on the extreme north east records low temperatures as low as 10F and some times the high also are less than 32 F. In the mountains the winter sets in October and lasts till April. The mountains are covered with a blanket of snow throughout the season.
On the coastline, the weather is even milder than the plains. Karachi, for instance records 77F as high in the coldest month and the low temperature is only 50 F. Actually the Arabian sea keeps the temperatures quite moderate. Once in a blue moon when cold air enters from the nearby Baluchistan Plateau, the weather becomes quite cool but even then the lows remain above 40 F.
In short the winter season is the best season in most of Pakistan and it is quite a contrast to the extreme heat for which Pakistan is well known.