So seasons are defined by temperature? In the UK we sometimes have our coldest weather in March. Does that mean the seasons have shifted? And what about countries close to the equator - do they have permanent summer? Seasons have nothing to do with temperature. Global warming is set to make that even more apparent.

>So seasons are defined by temperature?

In part. I'd say it's a combination of the temperature and amount of light you get per day.

The summer solstice around 20th June will always be mid-summer in the northern hemisphere even if it's freezing cold for the 45 days before and after. It's all about daylight and darkness. Nothing else.