Once upon a time, a tiny bird, the halcyon (kingfisher), went up to Zeus to complain.
I can almost imagine the scene: the plucky bird musters the courage to fly all the way up to the snowy peaks of Olympus, rings the door bell and is ushered in by a surprised Hermes, the gods’ messenger.
Upon shown into Zeus’s throne room, the tiny creature wastes no time in giving him a piece of her mind:
“How could you do this to me? You made me lay my eggs at the beach in January, but the cold, the rain and the surf destroy my nest and I lose my eggs and hatchlings. Is this how Mighty Zeus orders the world? It is unfair, that’s what it is. You gotta set this straight.”
Zeus is taken aback by the bird’s tirade (and quite amused by the tiny bird’s audacity, I imagine). But he also sees that the kingfisher is right, so he says:
“I cannot undo what has been ordained. But it is within my power to rule the weather and I decree that every year, in the middle of winter, there will be a spell of good weather for you to lay your eggs. Now go. Live long and prosper!”
And so it was done. Εvery year, in the middle of January, the skies clear up and Greece enjoys a spell of really bright, sunny days. The temperature ranges from 10 to 20 ⁰C (50-70 ⁰F), and it’s almost as bright as summer. In the morning it may be a bit chilly, but by midday people begin to peel off their jackets and scarves. Astonished tourists sun themselves in t-shirts and heavy boots. The trees begin to bud and some will even flower.
The phenomenon is is due to the Azores anticyclone settling over the Mediterranean in winter. It is so dependable, that ancient Athenians scheduled their mid-winter open-air theatre festival to coincide with the halcyon days. However the winter is far from over. Every sunny spell will sooner or later come to a cold and windy end and winter will have the land in its grip until March.
In the cold and stormy days that will follow, what will happen to the kingfisher and her eggs? Well, the myth is just that, a myth. The kingfisher lays her eggs in the spring, as most birds do.
How was it then connected to this weather phenomenon? Well, that was probably by association, as in mid-winter the star cluster of the Pleiades (one of whom is named Halcyon) is right in the middle of the sky.