Twilight is an intermidiate state of illumination where the sky is not completely lit nor completely dark. It occurs before sunrise and after sunset, and typically lasts for a couple of hours. In the Grand Theft Auto series, twilight typically occurs between 4:00 - 6:30 in the mornings and 19:00 - midnight in the evenings. Twilight plays a critical role in the game's appearance. During twilight, the sky may be illuminated with not only blue but also red, yellow, pink, purple and even green.
Types of twilight
Civil twilight in the Grand Theft Auto series typically occurs right after sunset (19:00) or right before sunrise (5:00 - 6:30) and typically lasts for about 30 - 50 minutes. The sky is bright during civil twilight, and headlights may not be necessary.
Nautical twilight in the GTA series occurs when the ambient lighting on the ground is dark and headlights are on when the player is driving a vehicle. This occurs at about 5:30 in the morning or 21:00 in the evening.
Astronomical twilight in the GTA series occurs when the sky is very dark but still somewhat illuminated, and stars ingame are visible. This occurs at about 4:30 in the morning or 21:50 in the evening.