Typically you must fly your drone during daylight hours. For night time flying, you can request a waiver.
You can fly during daylight (30 minutes before official sunrise to 30 minutes after official sunset, local time) or in twilight if your drone has anti-collision lighting. Minimum weather visibility is three miles from your control station. The maximum allowable altitude is 400 feet above the ground, higher if your drone remains within 400 feet of a structure. Maximum speed is 100 mph (87 knots).
You can request a waiver of most restrictions if you can show your operation will provide a level of safety at least equivalent to the restriction from which you want the waiver. Some of the most requested waivers are for operations beyond visual line of sight, during nighttime, and over people. See FAA DroneZone below for more information on requesting waivers.