hibernal (adj.)

• aestival
• algid
• arctic
• autumnal
• biting
• bitter
• bleak
• boreal
• brisk
• brumal
• canicular
• cold
• crisp
• cutting
• equinoctial
• frigid
• gelid
• glacial
• hiemal
• ice-cold
• icelike
• icy
• inclement
• keen
• nipping
• nippy
• numbing
• penetrating
• piercing
• pinching
• raw
• rigorous
• seasonal
• severe
• sharp
• sleety
• slushy
• snappy
• springlike
• stone-cold
• summery
• vernal
• wintery
• wintry