Learn Spanish (Latin America): La Navidad es en diciembre.

Spanish often requires a definite article (el, la, los, las) before the names of holidays, seasons, and days of the week. So, 'Christmas' becomes la Navidad.

Why do we use es here instead of está?

Even though estar is often used for locations and temporary states, we use ser (which es comes from) for dates, times, and telling when an event takes place. Since we are stating when Christmas happens, es is the correct choice.

Why isn't diciembre capitalized?

In Spanish, the months of the year (like diciembre) and the days of the week are always written with lowercase letters, unless they are the very first word of a sentence.

Does en always mean 'in' when talking about months?

Yes! Just like in English, you use the preposition en before a month to say that something happens 'in' that month, such as en diciembre.