The Navajo Times shared this:

Gháájí’ = October.
Translates to ‘Half’. Is meant that this is the month of the ‘Separation of Seasons’. In Diné culture, the beginning of the New Year begins in October.

HAPPY NEW YEAR everyone!

So there you have it – it is the Navajo New Year!

One thing of note, spelling varies, so Ghąąjį’ is also acceptable, as well as Ghaaji’.