The Summer Solstice marks the first day of summer in Anuire - now follows (comparatively) lazy days for the peasants as they wait for their crops to grow. It is a time of gaiety and - for the upper classes - diplomacy.
The day is oft called the Night of Fire - every year there is spectacular display of shooting stars that is visible if the weather is fair. Some years there is more activity than other years, but there is always some activity (truth be told there is often some shooting stars on the nights before and after the night of fire, but not as much).
The day is also known as Haelyn's festival, for all temples of Haelyn conduct a lengthy ceremony - starting at dawn and ending around midnight. The ceremony marks Haelyn's ascendancy over the other gods and his patronage of the Anuirean people.
As usual the Imperial city is filled with visitors - including numerous courtiers, envoys, and diplomats. There might even be someone from your domain there...