According our calender , Iranian calender (Solar), each season has three moths .
spring three months (each month 31 days) , summer three months (each month 31 days) , Autumn three months ( but each month 30 days) and finally , winter 3 months (each month 30 days) .
The first day of spring is our new year and i thing it's very beautiful because the Nature's liven and your new year are in the same time and it means a new life .
But the end of Autumn is Azar 30th or December 21st .
( The end of Autumn the longest night )
We celebrate the last night of Autumn because it's the longest night during each year and it's a Traditional celebration for Iranian , and we called this night YALDA (Yalda night).
It's a great night , Iranian families get together , generally in grandparents house and eat watermelon , black seeds and nuts , of course Watermelon is a traditional friut for this night and must be exist (delicious) and talk together , tell jokes , happy store and recollection .