I was surprised by the English Wikipedia (http://en.wikipedia.org/wiki/Autumn) and by Slashdot (http://slashdot.org/...re-Fall-starts-), that none of them mention September 21st as the start date of autumn.

In Europe, they say (although astronomically speaking it usually differs by a few days) that autumn starts on September 21st, winter on December 21st, Spring on March 21st, and Summer on July 21st. Compare the English Wikipedia article with the Dutch one for example (http://nl.wikipedia.org/wiki/Herfst), and note the table full of dates which are all a few days after September 21st.

Since nor the English Wikipedia, nor Slashdot, mention anything about the 21st, I assume in the United States this convention is not used?

So when does Autumn start in the United States? Or in <your country> if it's somewhere else? I'm unable to find this info in a clear way on the sites I linked!

Thanks!

I live in Atlantic Canada, so seasons are kind of vague. Fall starts at a variable time, when the leaves start turning. Winter comes when it fails to raise above freezing for more than a few hours, and snow starts to accumulate.

Spring comes when there is more bare lawn than snow drifts, and daylight is above freezing.

Summer,... it comes when it wants to and we get at least 5 days out of the week of 20C+ afternoons.

I thought the seasons were universal and scientific, weird.

I'm not sure the exact date but some leaves here are already starting to change (which makes no sense because it's still hotter than a cow's sack). So I would say it's going to be Fall soon.

I live in Sweden and here SMHI (Sweden's Meteorological and Hydrological Institute) defines autumn as when the average temperature is falling and is between 0 °C and 10 °C. This means that autumn starts at different dates in different parts of the country (It can differ almost 2 months between the north and the south parts). I think there are different ways to define autumn but this is definition that is mostly used in media in my country. Personally I feel that autumn starts when the leaf start to turn yellow/red.

I thought the seasons were universal and scientific, weird.

Oh, there are "Official" dates for season changes, but they really don't mean anything. They may as well be marked as "Day no one gives a damn" on calendars for all the effect they really have. We've had Blizzards in "Spring", and days in "Summer" which were barely above freezing at dawn.

In Europe, they say (although astronomically speaking it usually differs by a few days) that autumn starts on September 21st, winter on December 21st, Spring on March 21st, and Summer on July 21st. Compare the English Wikipedia article with the Dutch one for example (http://nl.wikipedia.org/wiki/Herfst), and note the table full of dates which are all a few days after September 21st.

That's just wrong. Isn't December 21st the winter solstice? i.e. the exact middle of winter, not the start.

I've always thought May 1st was the first day of Summer, but I'm sure there are differences. Read this which describes which months belong to which season (in North Temperate Zones): http://en.wikipedia....Spring_(season)

Since nor the English Wikipedia, nor Slashdot, mention anything about the 21st, I assume in the United States this convention is not used?

AFAIK, we actually do. I've always grown up hearing "Today is the first official day of summer!" and it's July 21st and it's already been boiling hot for a whole month. I always thought it was weird. Yes, those dates are supposed to be the peaks of the seasons (longest day of the year, shortest day of the year, and 12 hour days), so it makes more sense that they're the middle of the season rather than the start of the season. But for some reason I've just grown up hearing them labeled as the start of the season. Of course, I could have just grown up with a bunch of crazies.... it's possible, I guess.

[quote name='ChurchSkiz' timestamp='1315145259' post='4857484']
I thought the seasons were universal and scientific, weird.

Oh, there are "Official" dates for season changes, but they really don't mean anything. They may as well be marked as "Day no one gives a damn" on calendars for all the effect they really have. We've had Blizzards in "Spring", and days in "Summer" which were barely above freezing at dawn.
[/quote]

I'm not disputing the point of it, it's effing hot outside no matter what season it is right now, but I thought that the seasons were cooinciding with specific astronomical events dealing with the distance to the sun. ie Summer is the day the tropic of cancer/capricorn is closest to the sun, spring and fall are when they are halfway between Summer and Winter Solstice, etc.

March !

Its a mistake a lot of ppl in europe and NA make
Often they think summer starts on 21/22 june cause its thats what theyve always been told. Ive lived in europe for ~10 years it just make sense with what you experience.
But if you ask a climatologist from those countries they'll say 1st june (or there abouts).
Here in NZ I think its always been 1st june as the start of winter, like now its the 5th day of spring. Hard to argue for it still being winter for 2.5 more weeks when the new buds are out, lambs are being born, sun setting a lot later/rising earlier, & Im going outside in shorts and t-shirt
I assume give it some years and europe/NA will also adopt 1st june as the start, I assume here in NZ/oz etc since we're younger countries we're not so tied to tradition.

Im Ignoring tropical places where theres not 4 seasons