What are the EXACT dates for Seasons?

* Spring: March 20 - June 20

* Summer: June 21 - September 22

* Autumn (Fall): September 23 - December 20

* Winter: December 21 - March 19

Southern Hemisphere

* Spring: September 23 - December 20

* Summer: December 21 - March 19

* Autumn (Fall): March 20 - June 20

* Winter: June 21 - September 22