In South Africa, we always used to celebrate Spring Day on 1 September by being allowed to go to school in civies (usually shorts, T-shirt and slip-slops) provided we took a buck or two or tinned food for the poor. Applying a bit of logic, ie add 6 months because the seasons are reversed, that would make today spring day.
Well, it certainly is nice and sunny today, but I wouldn't even contemplate wearing shorts and slip-slops today; it was -2C whilst I was scraping the ice off my windscreen this morning.
I'm probably miles off spring day in the UK, but no one really acknowledges it here.
Anyway, it's spring day to me, and St David's day for the Welsh.