December brings the first frosts of winter to Las Vegas. December temperature averages by year in Las Vegas; High °F Low °F Year High °C Low °C; 58: 40: 2022: 14: 4: 58: 41: 2021: 14: 5: 59: 38: 2020: 15: 4: 56: 42: 2019: 13: 5: 59: 42: 2018: 15: 6: 63: 42: 2017: 17: 6: 57: 40: 2016: 14: 4: 56: 38: 2015: 13: 4: 58: 44: 2014: 15: 7: 57: 38: 2013: 14: 3: 57: 41: 2012: 14: 5: 56: 37: 2011: 13: 3: 59. December Mon Tue Wed Thu Fri Sat Sun 1 +72° +52° 2 +68° +52° 3 +68° +50° 4 +68° +48° 5 +72° +48° 6 +68° +52° 7 +63° +54° 8 +63°.