vesperasco

vespĕrasco, āvi, 3, v. inch. n. [vesper],

to become evening , grow towards evening : vesperascente jam die, Tac. A. 16, 34: vesperascente caelo, Nep. Pelop. 2, 5.— Impers. : vesperascit, Ter. Heaut. 248: ubi jam vesperaverat, Gell. 17, 8, 1.