A major change in the pattern will occur early next week

(CNN) — After weeks of spring warmth, parts of the United States will soon return to winter next week, with cooler temperatures possible across much of the eastern half of the country.

This Tuesday marks the official start of astronomical spring in the Northern Hemisphere after the warmest winter on record.

But it looks like Mother Nature has mixed up the seasons, as next week spring will feel more like winter. More than half of the US population will experience freezing temperatures or below.

The cold is not just an anomaly, it will threaten agricultural interests in the Southeast, where the growing season is underway.

The cold weather will come as a shock to many in the eastern part of the country who experienced warmer than average temperatures last week; The maximum temperature will be -6° this Saturday in many southern cities. But that changes this Sunday as cold weather begins to creep into the Midwest, moving south and east over time.

For this Monday, temperatures drop sharply and cold air spreads over the eastern half of the country.

Temperatures in St. Louis could drop more than 6 degrees, from a high of 15 degrees this Saturday to a low of 4 degrees this Monday. High temperatures in Atlanta could drop as low as 15 degrees this Saturday through Monday, from the low 20s to the mid 10s.

These temperatures may not be freezing, but are more typical of the heart of winter in parts of the South.

Memphis, Tennessee and Huntsville, Alabama are forecast to have a high of 10 degrees this Monday, which is normal for mid-January.

Cold air will move eastward Monday night into Tuesday, eventually reaching the Mid-Atlantic and much of the Northeast. New York will drop from a high of 15 degrees this Saturday to 7 degrees this Tuesday.

The high temperature in Philadelphia this Tuesday is expected to be 7 degrees, which is the normal high temperature for February 19.

Low temperatures will also decrease. Temperatures in the Southeast this Tuesday morning will be -12° to -9° below normal for this time of year. Temperatures are expected to drop as low as -1°C this Tuesday morning in Atlanta, Charlotte and Birmingham, Alabama, posing the greatest risk to plants.

Bringing plants indoors is the easiest way to protect them from severe frost, but if you can’t do that, covering them can also help.

Sheets, towels, or blankets can be used to help trap radiant heat from the soil around the plant. Use stakes with your plant covers or place them on patio furniture so they don’t crush the plants.

Temperatures will rebound fairly quickly in the Southeast by the end of the week, so hold on to that sunscreen and allergy medicine because spring will soon be in full swing.