From Halopedia, the Halo wiki
Universe and lore
The map is set in an open environment with many openings and chasms, for a diverse amount of combat in a Forerunner environment on an unspecified Halo installation, in a complex of structures comprising a part of the ring's weather control system.
One side of the map opens to an open beach, with towering cliffs and a river on the other side. The terrain rises near the center where several large rocks provide cover. On opposite sides of the center are two large Forerunner structures, serving as the bases, accompanied by smaller structures and passageways around them. Connecting the main structures is a beam of energy that will disable any aircraft passing through it with an EMP. Man Cannons located on the side structures allow fast access to the flanks of each base. An additional Man Cannon at the front of each base launches players to their Machine Gun Turret situated atop a rock overlooking the central battle. On both sides of the map, small caves serve as alternate routes to the bases. There is also a crashed Longsword providing cover on the beach side.
The following are locations on the map that are so named on the player's heads-up display during gameplay:
Tempest is considered to be a map intended for Forging on, albeit not as extensively as Forge World. The map retains most of Forge World's large item palette, and is one of two maps planned to support the Thorage functionality in the upcoming Forge update for Halo: Reach as part of Halo: The Master Chief Collection.
The working title for Tempest was "DLC Medium".