Spring-Winter?

I'll start with a big Thank You for all the love shown to my aurora borealis blip. It's very rarely I make it that high (page 2) on the popular pages. And now to a new subject...
Is it winter? Well, obviously it is. The ground is covered in a thick layer of snow. The temperature is above freezing in the day, but well below most nights. The weather forecast predicts snow, rather than rain. Snowdrops and crocus are still many weeks away.
Is it spring? Well, obviously it is. The snow is melting and things (such as rubbish bins) appear back into the light. Each tree has its own ring of melted snow, perhaps even a ring of bare ground. The sun is warm enough that thick jackets can be left behind. If you can find a sheltered south-facing spot you can sit there in the sun, no jumper needed, and drink a relaxing cup of tea.
Welcome to the 5th season in sub-artic and artic areas. In Swedish it is called "vårvinter", literally spring-winter. The Local, a Swedish magazine written in English has a good description of this varvinter time of year.
I felt this 5th season arrived for few days ago now but it really is TOO early so I've resisted tagging my pictures this way. Now it's March so here goes.
In Alaska they talk of the dark winter and the light winter, another way of splitting up the winter into these two very different seasons.
I wonder how it is elsewhere? I was once on Crete in late September and after almost tropical rainstorms the dry brown of summer turned a beautiful green as autumn flowers bloomed and grass returned. Is there an "autumn spring" in some parts of the world? Who decided there were only 4 seasons?