From a derivative of cheo (to pour; akin to the base of chasma through the idea of a channel), meaning a storm (as pouring rain); by implication, the rainy season, i.e. Winter -- tempest, foul weather, winter.
a. stormy or rainy weather, a tempest (so from Homer down): Matthew 16:3 (Tdf. brackets WH reject the passage); Acts 27:20.
b. winter, the winter season (so from Thucydides and Aristophanes down): John 10:22; 2 Timothy 4:21; χειμῶνος, in winter (-time), in the winter (Plato, de rep. 3, p. 415 e.; Xenophon, mem. 3, 8, 9; others (cf. Winers Grammar, § 30, 11; Buttmann, § 132, 26)), Matthew 24:20; Mark 13:18.