A weather radar includes an antenna unit of an active phased array system in which a plurality of antenna elements configured to transmit a radar pulse and receive a reflected pulse are arranged in a vertical direction, a transmission beam formation unit configured to divide an observation range in the elevation angle direction into a plurality of observation elevation angles, subdivide each observation elevation angle into a plurality of regions, assign a set of a plurality of regions not adjacent to each other to a pulse repetition interval (PRI), and form a fan-shaped transmission beam in the elevation angle direction for each of the regions in the set, and a reception beam formation unit configured to form a plurality pencil-shaped reception beams for each of the plurality of regions.