Diving Into the Average First Freeze Dates Around the U.S.

There is no doubt that fall is in the air. The Northeast, the Great Lakes, the Midwest, and the Pacific Northwest have all experienced some degree of fall temperatures over the past few weeks. While bursts of cooler temperatures have been followed up with warmer readings, there will come a time when the cool weather is here to stay. This is about the time when parts of the country will begin to see the first freeze of the season. When can you expect this to happen in your neck of the woods? Read on for all of the details.

Most Parts of U.S. See First Freeze During the Fall

The fall season is when most of the U.S. will experience the first freeze of the season. As expected, the top terrains and the northern edge of the country will see the temperatures plummet first. You can expect some areas to see the first freeze in September, gradually moving southward in October and November.

The first freeze is defined as when the mercury dips to a level of 32 degrees or lower for the first time in the season. This is the benchmark in which you can expect damage to unprotected plants. The damage is more likely if the temperatures linger at this level for several hours.

The most predictive factor of when you can expect the first freeze is the elevation of any given area. According to historical data from the National Oceanic and Atmospheric Administration (NOAA), the first 32-degree readings of the season typically happen at about the first day of fall in the higher elevations out West. Areas near the Canadian border should also prepare for the first freeze of the season to happen in the days surrounding the first days of fall.

The bulk of the Northeast and the Midwest will see the season's first freeze by the time that October comes to a close. The northern fringes of the South will also see the temperatures dip below this level by the end of October. The warmer coastal areas of the mid-Atlantic and the Deep South generally have until the beginning of November before this event happens.

It is also typical for urban and coastal areas to experience the first freeze at a later date when compared to rural locations or communities located farther inland. There are a number of factors that influence this phenomenon. For example, the urban heat island effect works to keep bigger cities warmer than the surrounding suburbs.

In addition, the warming impact of oceans and other large bodies of water also keep nearby areas warmer. This is why coastal areas tend to record the first freeze of the year slightly later than other locations just a bit inland.

Looking at a few specific average first freeze dates, those in Chicago should prepare for an average date of October 19. Minneapolis comes in slightly earlier at October 13 due to its location farther to the north. The higher elevation in Denver translates to an average first freeze date of October 7. Meanwhile, Philadelphia comes in at November 11. Heading to the south, Atlanta typically experiences its first freeze around the date of November 16 while Dallas' average is November 23.

It is important to note that the first freeze can vary significantly from year to year. Predicting the first freeze is not an exact science as varying weather patterns can greatly influence the timing of these events.

Why is it Important to Know When to Expect the First Freeze?

Even a bit of frost can cause damage to vegetation when temperatures are still hovering above freezing. Temperatures that fall below the freezing mark have the potential of completely killing plants and other types of vegetation. Frost is mostly likely to occur when the temperatures hover between 33 and 36 degrees.

A frost generally results in minor levels of damage to vegetation. However, a hard freeze of temperatures registering at 28 degrees or colder will usually completely destroy most types of vegetation and plants.

Even plants that are considered to be hardy in your location can be susceptible to damage, particularly if planted in a container. This is because the roots in pots are not able to acclimate when the temperatures fall below freezing. You can protect these vulnerable plants by bringing them indoors if possible. As an alternative to dragging your potted plants inside, you can protect them from the bitter winds by putting them under a covered patio. Moving the plants closer to the house will also help support a warmer environment than leaving them out in the open.

Keep in mind that some plants will automatically go dormant in the winter. You can keep these plants in a garage or basement until the temperatures warm up in the spring.

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