When is the first day of fall 2013?

In the Southern Hemisphere, fall 2013 begins on the 21st of March in New Zealand, Samoa, Tonga and Kiribati and on the 20th of March everywhere else.

In the northern hemisphere, fall 2013 begins on the 23rd of September in time zones east of and including UTC+3.5 and on the 22nd of September in time zones west of and including UTC+3.