The Sun has reached its highest point in the sky, marking the beginning of astronomical summer and the longest day of the year. Solstice means “standing still” – a day when the path of the Sun across the sky does not appear to be moving up or down.
From now until 21 December, the Sun’s path will appear to move closer to the horizon and days will become shorter. This will happen in small amounts (a few minutes) especially at first, but the nights are already drawing in.
The atmosphere and oceans take time to warm up, so this is not usually the warmest part of the year, which is still to come.