(a.) of or pertaining to winter.

Siberian aestival algid arctic autumn autumnal below zero biting bitter bitterly cold bleak boreal brisk canicular cold cold as charity cold as death cold as ice cold as marble crisp cutting equinoctial freezing freezing cold frigid gelid glacial hibernal hiemal hyperborean ice-cold ice-encrusted icelike icy inclement keen midsummer midwinter nipping nippy numbing out of season penetrating piercing pinching raw rigorous seasonal severe sharp sleety slushy snappy solstitial spring springlike stone-cold subzero summer summerlike summerly summery supercooled vernal winter winterbound winterlike wintery wintry