Learn Turkish: Sonbahar eylül ayında başlar.

In Turkish, you can say eylülde (in September), but it is very common to say eylül ayında, which literally translates to "in the month of September". To link eylül and ay (month), Turkish adds the possessive suffix -ı to make eylül ayı.

How do we get from ay to ayında?

Let's break it down. ay means "month". The -ı links it to September to form eylül ayı. The -da is the locative suffix meaning "in". When adding a location suffix like -da to a word that ends in a possessive suffix like -ı, Turkish requires the buffer letter -n- in between. So it becomes ay + ı + n + da.

Why is eylül (September) not capitalized here?

In Turkish, months of the year and days of the week are only capitalized if they are part of a specific date with a number, like 15 Eylül. Because we are talking about September in general, it starts with a lowercase letter.

Why does the verb use the -r suffix in başlar?