Weather

Weather and time of day are one of the game's weather templates. The server keeps it: players who join later get the same.

In a script

world.setWeather("DTFreerideNight")   -- night for everyone
print(world.getWeather())

-- day and night every 30 minutes
local night = false
timer.every(30 * 60 * 1000, function()
    night = not night
    world.setWeather(night and "DTFreerideNight" or "DTFreeRideDay")
end)