In early to mid-November, winter seemed in command from the Mountain West to the Central Plains. Ski areas rejoiced in record high-elevations snows while Montana residents shivered in temperatures as low as minus-20. But in the past week, winter has altogether vanished.

The cold and snow in the Rockies are gone and historically warm weather has taken over. Abnormally warm weather has not only invaded the Mountain West, but also the entire region from the Desert Southwest to the Northern Plains. Scores of records were set Monday, from Arizona to North Dakota, and in some areas, temperatures were nearly 40 degrees warmer than normal.

Most notably, Denver soared to 81 degrees, its warmest temperature ever recorded during the month of November, some 34 degrees above normal — breaking the record set just last year. Here are some other remarkable record highs that were set:

Monday’s long list of record highs marked the fifth straight day of remarkably warm weather in the western half of the nation. The heat first arrived in Southern California about a week ago. On Wednesday, Anaheim surged to a record high of 100.

Then, the heat pulsed to the east and northeast. In Montana alone, Nov. 22-25 brought 83 record highs, and 84 record warm low temperatures. On Thanksgiving, Glasgow, Mont., broke its record high by 10 degrees according to Tanja Fransen, meteorologist-in-charge at the National Weather Service office serving the region.

Meanwhile, Cheyenne, Wyo., logged its latest 70-degree reading on record Sunday when it soared to 71, noted Weather Underground’s Bob Henson.

In the past week, 1,669 warm weather records have been set in the Lower 48 compared to just 26 cold weather records.

All of this record heat has decimated the nation’s snow cover. On Nov. 8, 25.9 percent of the nation was covered in snow. That number is down to 8.5 percent as of Nov. 28 — the lowest since records began in 2003.

The weather pattern flipped in response to a change in the jet stream. In the first half of November, the jet stream plunged into the northwestern third of the nation, allowing blasts of Arctic air to come south. But it has since retreated and a sprawling heat dome has occupied much of the region.

While temperatures have seesawed this month in the Northern Rockies and Northern Plains in response to changes in the jet stream, the heat has been a persistent feature from the Desert Southwest to the Southern Plains.

For the first time on record, Phoenix may not post a single November day with an average temperature below 65 degrees, while many sites in the Southwest are set to post their warmest November on record.

Abnormally warm weather may persist in many parts of the western states through at least mid-December as weather features align to direct cold weather into the eastern U.S. while keeping the West warm.

All of the record high temperatures set in recent days fit into the long-term pattern of climate warming. About 4,500 record highs have been set this month compared to only about 1,600 record lows. This month is set to become the 36th straight month with record highs outnumbering record lows, according to meteorologist Guy Walton, the longest streak in history.