Today marks the fifth day ("pancami") of the Vedic month of Magha, and is the official beginning of springtime ("vasanta"). Although it may not feel like spring in many parts of the world.
Srila Prabhupada says this about the month of Magha in Bhagavad-gita As It Is:
"According to Vedic injunction, one has to take his bath early in the morning even during the month of Magha (January-February). It is very cold at that time, but in spite of that a man who abides by the religious principles does not hesitate to take his bath."
—Bhagavad-Gita As It Is, 2.14