Zikan without going into much detail, I can tell you that the most modern UAV's have no trouble operating at night in total darkness, and inclement weather... they fly for the most part on auto pilot to the target zone using GPS, and other gear. They are of course equipped with all manner of sensors including radar, FLIR, laser rangefinders, and so on...
They can, do, and will continue to operate at night... and the badguys cannot hide from them. And keep in mind they are now being armed with air-launched weapon as well, and have used them to kill quite a few of the enemy in Afghanistan.