How are the seasons defined officially in your country/state? (snow, hot)

[Ariete]

Originally Posted by Rozenn

Then make it 12.83°C or something. 4 months of summer kinda dilutes the whole concept.

I know, and that also makes spring and autumn quite short.

Ok, 12.83C sounds a bit better, but works better in spring. It means that summer started on June 10th and ended on September 19th.
The 10C period was between May 15th and October 5th. And yes. Summer. In October. In Finland.

Originally Posted by B87

Those growing season temps sound too low. If the growing season = mean of 5C then we have a year-round growing season, which is hardly the case.

Oh, yes. Here, the growing season ends when there is a prolonged period of frost or snowfall. If you use the same for England, it would have a start and end every year. In most areas, at least.

[french user]

Originally Posted by Ariete

Some speculation about the seasons again, and I'm curious how the seasons are defined in your country meteorologically, or are there any official methods? Or is it just Dec-Feb winter, Mar-May spring and so on? (Or Dec-Feb summer for you living down under.)

We use the following definitions:

Winter: mean daily temp below 0C
Spring: mean daily temp 0-10C
Summer: mean daily temp above 10C
Autumn: mean daily temp 0-10C

The season starts when the temps are above/below those figures for at least 7 days in a row, and the seasons can't be reversed even if it warms up/cools down again. Sweden and Norway also uses these same criteria.

Concerning France I have never heard of those definitions. meteorological seasons are usually considered to be spring: March, April, May summer: June, July, August etc. But most people usually refers to the astromical seasons, starting in the solstices and equinoxes.

If I apply your seasons definition where I live (Loire Valley in central/northwestern France) it would be spring from the end of december to February (with many days above 10°); then summer from March to the end of November !

Originally Posted by Ariete

Last question: what is required for a heat wave? 25C? 27C? 30C? 90F? For how many days in a row?

Here, it should be above 35°C in the daytime, with no temperatures below 20°C in the night for at least 3 consecutive days.

[dunno what to put here]

For my region, the heatwave threshold is 29C (day) and 15C (night). Personally, I think this should be higher, the heat in Yorkshire can easily match the SW of England, and is usually hotter than NW England.

[Ariete]

Originally Posted by french user

If I apply your seasons definition where I live (Loire Valley in central/northwestern France) it would be spring from the end of december to February (with many days above 10°); then summer from March to the end of November !

Perhaps I was unclear, the 24h temperature has to be permanently above 10C. A day with a max of 15C and low of 5C has a mean of 10C. A day with a high of 12C and low of 4C has a mean of 8C. Places like Tours or Angers have probably a 'spring' most of the winter, but snowfall and prolonged freezing temps (that you had recently) changes the season.

Like I said, the seasons can't be reversed back, and springlike temperatures in winter or summerlike temperatures in spring or autumn are common here too. They are just not permanent, so they are part of the season

And of course different climates, different definitions and results. In Singapore, our July would be an unusually cold winter month.

I didn't mean our classification of the seasons is correct or the best one, as I said to Rozenn, those classifications give misleading results here as well. As last year's 'summer' lasted until early October, or 2008 had a winter of only two weeks. I was curious to know if other countries have similar or other classifications.

[deneb78]

Originally Posted by P London

Winter starts on December the 1st etc but I think it goes like this:

December 15th to February 20th (winter) Stupid atlantic fronts that halts winters Urgh mild **** gets so boring!!

February 20th to may 10th (spring)

may 10th to september 7th (summer)

september 7th to october 1st. (interautumn) Those stupid indian summers.

1th october to 15th December (autumn)

I think we have patchy seasons. For example I think Autumn in London is from October to February between those months we get patches of real winter mixed in.

This sounds more or less how it is in Vancouver. But I think our heatwave definitions are different. Usually we have heat alerts if the temp is over 28C in summer LOL

[SophieLL]

Summer here starts 1st of november. This is when temp above 30c start to happen and heatwaves can occur. It ends in the end of March, so thats 5 months.

Autumn starts in April and it ends when June starts (2 months): this period is usually warm and comfortable. Days are usually warm in the mid 20s, while nights are usually cool, between 10 and 17c. nights of less than 10c can occur in May.

June and July are the winter months: the only months where consistent cold can occur. I mean weeks of "cold" (for BA standards) weather. I did a test last year to see if June and July could score two months with NO 20c nights, and they failed, but, tbh, only one night in July temp was 20c, and the rest of the month was consistently cold to cool. Both months are dry and if they are sunny (like 2012) they can be outstandingly beautiful. They have by far the best climate.

August is a transition months. August can easily have periods of hot weather (like 30c) cause theres a phenomenon that ocurrs every year near the end of August thats called "Tormenta de Santa Rosa" and before that we have a period of spring like temperatures, even summer like some days. Temp can easily reach 30c and be warm for plenty of days.

September and October are spring months: nice, sunny and warm, usually very comfortable. October can experience hot days but nothing too crazy.

A heatwave i think is 7 days with temps above 30c? or something like that?
Right now we are in orange alert of heatwave but we ve only had like maybe 4 days of hot weather? High heat index (near 40s) and high humidity and temps between 30/35, i think we are in orange cause days are getting hotter and will be hotter until a storm appears.
Heatwaves are very normal in the summer, and high heat indexs too (we had 46 heat index in christmas!).
I usually hate summer and the bad thing is that is the longest period of the year. Every other season lasts much less. Thats why a/c is a really good investment here, you will use it MUCH more than a heater. I dont own a heater and never needed one.

[SophieLL]

To compare London summers to BA climate in general (i think London haves great summer temps):

The hottest London summer month (July) haves similar temps to October, a spring month in Buenos Aires.
May (spring-summer month in London) in London is colder than May in Buenos Aires. May in London is spring/summer, while May in BA is autumn/winter. May temp in BA is 10/19 and in London 8/17.
June/August and September in London (the other summer months) are colder than BA April (autumn month).
October in London (autumn month) is colder than June in BA (winter month).
November in London (autumn) is colder than the coldest month in BA (July)


So, basically London summer resmemblances BA autumn, saving for July, that resemblances BA October, a very comfortable spring month.
The summer or winter temps of the cities are not comparable (London winters being colder than anything BA gets, BA summers being way hotter than anything London will ever get). Lucky for them .

I used this to compare them both:

Buenos Aires - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/London#Climate


One of my favourite person in the whole world, is gonna go from BA to live in London next August , and we will talk a lot about weather (he loves talking about weather too) via skype! so im preparing myslef

We are already discussing it, like saying how much he will enjoy summer, and if he will miss hot afternoons (i know i wouldnt ) and how cold the winters are gonna be, etc.

[Joe90]

The seasons are in neat 3 month periods here. Dec-Feb for summer, Mar-May for autumn etc. Only boffin types would usually refer to astronomical seasons.

No heatwave threshold for here that I'm aware of. Probably because there aren't heatwaves in this part of the country.

10C/50F is used for the growing season in my area of expertise, although it doesn't really mean much. Lots of stuff will grow year round.

[P London]

Originally Posted by deneb78

This sounds more or less how it is in Vancouver. But I think our heatwave definitions are different. Usually we have heat alerts if the temp is over 28C in summer LOL

Our heatwave threshold is 32c/18c which seems a bit high. I would call anything above 28c here a heatwave if its prolonged.

[wawa1992]

I don't know what it is officially, but to me (White House, TN)

Winter - average high temps <55 F
Spring/Autumn - average high temps 55-79 F
Summer - average high temps >80 F

Winter: November 30th - February 23rd
Spring: February 24th - May 21st
Summer: May 22nd - September 23rd
Autumn: September 24th - November 29th

Of course, it has seemed to be warmer in recent years, and these are averages. An individual day can (and often does) have a high temperature in another season's range. For instance, May 4, 2012 (the day I got my first car) was a spring day, but it had a high of 87 F.