Today is the first day of summer in Iceland, but it has nothing to do with weather, i.e., wind and temperature. It is merely the fact that in the old Icelandic calendar there were only two seasons, i.e., summer and winter. Harpa, or English Harp, is the name of the first summer month, and it always starts on the first Thursday after April 18th.
The people of Iceland always find a way to be optimistic. If the weather is good on this day, like today, then we are of course happy and hope for all the summer to be like this. Then there is this saying that if summer and winter freeze together the night before, it means that the summer will be really good. To check this, you put out a bowl of water in the evening and check it early next morning for ice. Well, last night, it only froze further inland, but who cares, the weather is nice now.
Then there is the definition of good weather. In the old days, it all depended on what was good for the animals, but now we want it to be sunny and warm. Back then, actually, if the spring was cold, it meant that the grass would grow slower and be richer for the animals when cut for hay. Rain is also good for the grass to grow, and back then, this was almost the only thing people would cultivate in Iceland. Grass for animals.
We now welcome people to Iceland to enjoy the midnight sun and the never ending night from mid May to mid July.