Even in Denver, the transition from summer to winter is usually a tad smoother than this.

At 3 p.m. on Wednesday afternoon, Denver’s high temperature maxed out at 83 degrees. By 9 a.m. on Thursday morning, the temperature had plummeted all the way down to 19 degrees.

That 64-degree swing in 18 hours made it Denver’s largest two-day October temperature switch on record, and one of the greatest temperature changes in the city’s recorded history.

It’s also Denver’s greatest temperature change in nearly five years, going back to a 65-degree flip in January 2015. It’s now also tied for the 15th-greatest two-day temperature change in Denver’s recorded history.

A powerful cold front dropped temperatures in a hurry on Wednesday evening, kicking up dust and drawing in gusty northerly winds. In the first hour after the front moved through, temperatures had already fallen a full 18 degrees at Denver International Airport, and temperatures continued to rapidly plummet. In just 12 hours, temperatures fell 57 degrees at DIA, making it the greatest October temperature switch in recorded history.

Not for October specifically, but it appears the 19th of October in 2010 saw a 55 degree difference, that could be the biggest Oct swing we have on record. — NWS Boulder (@NWSBoulder) October 9, 2019

That same system brought in a hefty burst of rush hour snow on Thursday morning, leading to a widespread 2-4 inches of snow across the metro area.

Temperatures likely haven’t stopped falling, either. Once clouds clear on Thursday night, the mercury will plummet even further, perhaps as low as the single digits. A fresh snowpack, coupled with clearing skies and dying winds will create ripe conditions for additional cooler weather tonight, and that could put more temperature drop records in sight.