Seventeen inches of snow in Wyoming, the earliest snowfall on record for New Mexico and the earliest flakes in decades for parts of Colorado — these are just a few of the astonishing weather reports coming out of a record-setting September week.
On Wednesday morning, snow was falling over parts of Colorado and 5 million people remained under winter weather alerts across portions of the Northern and Central Rockies. Those in the Denver area woke up to 1 to 4 inches of snow coating trees and grassy surfaces.
A few more inches of snow was possible, mostly at the highest elevations, before the snow was expected to end by afternoon.
In addition to parts of Colorado and New Mexico experiencing their earliest snow on record, the weather had whiplashed in just days from record-setting temperatures near or exceeding 100 degrees, to the sudden winter blast.
Rapid City, South Dakota, set a U.S. record for the fastest turnaround between 100 degree temperatures and measurable snow, after it hit 102 degrees F on Saturday, only to then see an inch of snow on Monday. This two-day gap broke the record for shortest amount of time between those two weather observations, the previous record being Ardmore, South Dakota, in September 1929 when a similar event took place over the course of approximately three days.
Rapid City also topped the list for greatest temperature drop. After setting an all-time September high on Saturday, the temperature dropped more than 70 degrees in two days, also setting a record for earliest first freeze on Monday.
With 2 to 5 inches of snow blanketing Boulder, Colorado, the area saw more snow on Tuesday than Washington, D.C., and Philadelphia saw all of last year, combined.
Here are the top snowfall totals for each state:
Wyoming: Casper 17 inches
Montana: Red Lodge 15.5 inches
South Dakota: Terry Peak 15 inches
Colorado: Alamosa 14 inches
New Mexico: Canon Plaza 5 inches
In addition to the snow, temperatures 30 to 40 degrees below average will lead to numerous record lows and record cold highs Wednesday and Thursday morning. Highs on Wednesday across the Rockies and Plains will only get into the 40s and 50s, and lows Thursday morning will dip back down into the 20s and 30s.
This chill in the air won't last long, however, with temperatures expected to rebound to the 70s by Friday and 80s by Saturday in Denver.