Learn French: Nous sommes en janvier et en février.

In French, it is very common to use Nous sommes (literally "We are") to express the current date, day, or month. While English says "It is January," French expresses this as being in the month: Nous sommes en janvier.

Why do we need the word en here?

To say that something is happening "in" a specific month, French uses the preposition en. You cannot just say Nous sommes janvier. You must say Nous sommes en janvier.

Why aren't janvier and février capitalized?

Unlike in English, the names of months and days of the week are not capitalized in French unless they happen to be the very first word of a sentence.

Could I say Il est instead of Nous sommes?

No, you cannot use Il est for dates or months. Il est is used for telling the time, like Il est trois heures (It is three o'clock). For months and dates, always use Nous sommes or the more casual On est.