The Ethiopian calendar is a solar calendar and it is the main calendar used in the country. It has 12 months of 30 days plus five (or six if it is a leap year) other days that make a 13th month. This short month is called Pagumiene and it comes after August and before September.

The first day of a new year in Ethiopia is September 11 in the Gregorian calendar, except when it is a leap year; then it is September 12. Ethiopians celebrate 12 public holidays, including Christmas Day on what would be January 7 according to the Gregorian calendar. For Ethiopians, Christmas Day falls on December 29.

There are 12 hours between sunrise and sunset all through the year and the time is three hours ahead of Greenwich Mean Time.
https://rainbowftf.ngo/the-ethiopians/ethiopian-calendar/