The english description of season times on Wikipedia is explained in a more complicated way and it also depends where you live and which tradition you use.
In the Norwegian description it says:
English translation (Google Translator):
Astronomical seasons
From what is explained above about the Earth's orbit around the sun, and if we define summer as the lightest and warmest time of year and winter as the darkest and coldest, the astronomical seasons will be as follows:
* Spring. From approx. 5. February to approx. 6. May. (midpoint = equinox = ca.21. March)
* Summer. From approx. 7. May to approx. 6. August. (midpoint = summer = ca.21. June)
* Autumn. From approx. 7. August to approx. 16. November. (midpoint = autumn equinox = ca.23. September)
* Winter. From approx. 17. November to approx. 5. February. (midpoint = winter solstice = ca.22. December)
For some purposes the year is divided into two parts, summer and winter. The astronomical section will then be:
* During the summer months. From the spring equinox (ca.21. March) to autumn equinox (around September 23).
* Winter season. From the autumn equinox to spring equinox.
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EDIT:
Meteorological (Translated from Wikipedia.no):
* Winter = december, january, february
* Spring = march, april, may
* Summer = june, july, august
* Autumn = september, october, november
Half-year season (Translated from Wikipedia.no):
* Summer half-year from ca. 16. april to ca. 17. october.
* Winter half-year from ca. 18. october to ca. 15. april.
It doesn't say which solar term/tradition we use but it says this is what most uses exept from some tropical and subtropical zones.
Tropical zones are places where non of the 12 months sinks below +18 °C (average through the month). Tropical areas are around equator.
Subtropical zones are places where the warmest month never goes below +20 °C and the winter is mild and does not last for long. Subtropical areas are: http://upload.wikimedia.org/wikipedia/commons/4/44/Subtropics.png