Learn Danish: Det regner mere og mere om efteråret. - It rains more and more in the autumn.

In Danish, the preposition om is used with times of the day, days of the week, or seasons to describe a recurring or habitual event. Here, om efteråret means that this happens generally every autumn, not just one specific time.

Why is the definite form efteråret used instead of just efterår?

When using om to talk about recurring seasons or times, Danish requires the noun to be in its definite form. You take the neuter noun et efterår and add the definite suffix -et to make efteråret.

If om efteråret means it happens every autumn, how would I say it is raining a lot this autumn?

To talk about the current or upcoming autumn, you would drop om and say til efteråret (if it is approaching) or i dette efterår (this autumn). The phrase om efteråret is strictly for general, repeated occurrences.

Does the phrase mere og mere work exactly the same as in English?

Yes, it translates directly! Mere is the comparative form of meget (much). Just like in English, repeating the comparative with og (and) shows that an action or state is continuously increasing over time.