Time is a factor in the Grand Theft Auto Universe. In the GTA III era, time moves at a rate of one second in real time is one minute in-game, making one in-game hour a minute and one in-game day 24 real time minutes. In Grand Theft Auto IV, time moves at a rate of two real time seconds to one in-game minute, meaning that one full day is doubled from 24 real time minutes to 48 real time minutes. Time is in 24-hour time in the game, starting at 00:00 and going to 23:59 at midnight.
In the games, especially Grand Theft Auto: San Andreas, the day-and-night cycles along with the weather moves along with the time.