During the summer solstice, which occurs around June 21st each year, the Sun reaches its highest point in the sky as seen from Earth. This means that the days are at their longest during this time, and the nights are at their shortest. In Ireland, this can result in daylight lasting until as late as 10:00 PM or even later in some parts of the country.
As the summer progresses, the days gradually start to get shorter, and the nights start to get longer, until the autumn equinox occurs around September 22nd, marking the official start of autumn.