First fall frost date

When will we see the first fall frost in Maryland?

To find your average first frost date, enter your location or zip code into the frost date app from The National Gardening Association: https://garden.org/apps/frost-dates/.

You will receive a chart like in the example below:

The chart indicates a 10% chance that the temperature will go down to 32°F on October   There is a 90% chance that it will be 32°F on November The data is derived from the – U.S. Climate Normals from NOAA.

Two things to keep in mind:

1. The likelihood of frost will vary between landscapes in the same town or even neighborhood, due to many factors such as, changes in wind, elevation, and proximity to buildings and water;
   
2. The surest way to know when the first frost is expected is to closely monitor weather conditions using weather websites or your local news reports.

Why do gardeners care about the first frost? 

Very tender annual plants like basil, tomato, cucumber, pepper, zinnias, and marigolds are damaged or killed by freezing temperature. Plan to gather your final harvest before the first significant frost. Pumpkins, winter squash, white potatoes, and sweet potatoes can also be injured by a heavy frost. Cold temperatures will improve the flavor and texture of kale, collards, cabbage, and turnip greens. Bring tender indoor plants and annual flowers like geraniums and begonias indoors before the first frost if you plan to keep them growing indoors through the winter.

Canada Hardiness Zones

The ‘Plant Hardiness Zone Map of Canada’ outlines the different zones within Canada in which various types of trees, shrubs and plants will most likely survive. It is based on the average climatic conditions of each area and is an excellent starting point if you are wondering if a particular plant will over-winter (survive the coolest temperatures) in your area.

By using this map, you can choose the best plants that will be more likely to thrive in your location. For example, when Veseys lists a perennial plant as being suitable for Zones , this means that if you live in an area within that range, this plant would be suitable for your location.

The data and zone map information here simply reflects the most recent data collected and presented by Natural Resources Canada. Gardeners should understand that this map is a guide only – not a guarantee of gardening success, as climatic conditions are constantly changing and there are many other factors that can affect the success and failure of plants. As well as using this map for reference, we recommend consulting other gardeners who have ‘hands-on’ experience of weather and gardening patterns in your area.

Along with year-to-year variations in weather, microclimates can also play a role in determining the right plants for your garden. Microclimates, which are small areas of varying weather conditions within larger zones, can be caused by local geography of the area such as hills and valleys as well as variations of solar and wind exposure. Even buildings and pavement in urban areas can create relatively small microclimates that can potentially produce different gardening results.

The newly amended Canadian Hardiness Zone map is divided into ten major zones: the hardiest is 0 and the mildest is 9 (the southern tip of Vancouver Island). Relatively few plants are suited to zones 0 and 1.

Credit: Illustration by Waterbury Publications Inc

First Freeze Map and Average Frost Dates

Find Your USDA Plant Hardiness Zone

Microclimates

close up of zinnia with frost on petals

Credit: Sandy Sarsfield/Getty Images

Plants That Won't Survive a First Fall Frost

The fall of has been warm across the Mid-South. Across the Mid-South at our climate sites; Jackson, Tennessee, had the lowest temperature this fall on October 22 of 36 degrees. Depending on the moisture that morning there may have been a frost. Most other places in the Mid-South haven't been below 40 degrees.
In looking at past data we are just about the point in the year were locations are seeing their average time for the first freeze, yet many haven't even had temperatures in the 30s yet. So here is a look at typical "frost" and freeze dates for the climate sites in the Mid-South.

Here are the earliest and latest "frost" and freeze dates along with the average date for the first "frost" or freeze in the fall and the last "frost" or freeze date in the spring.

• The freeze date is the date of the minimum temperature being 32 degrees Fahrenheit or below.
• The "frost" date is the date of the minimum temperature being 36 degrees Fahrenheit or below. Note: Frost is also dependent on moisture so this "frost" date is just an estimate.

"Frost" Data

First Fall "Frost"

Last Spring "Frost"

Freeze Data

First Fall Freeze

Last Spring Freeze

The dates listed are normal averages for a light freeze/frost. The possibility of a frost occurring after the spring dates and before the fall dates is 50 percent. Frost/freeze temperatures are categorized by their effect on plants:

• Light freeze: 29 degrees F to 32 degrees F – tender plants killed, with little destructive effect on other vegetation.
• Moderate freeze: 25 degrees F to 28 degrees F – widely destructive effect on most vegetation, with heavy damage to fruit blossoms and tender and semi-hardy plants.
• Severe freeze: 24 degrees F and colder – damage to most plants.

*Higher elevations in Hawaii do occasionally see at-or-near freezing temperatures but definitive frost dates are not available.

Courtesy of the National Climatic Data Center, National Oceanic and Atmospheric Administration.

Hawaii

Use our Frost Dates Calculator to find the average dates of the last light freeze of spring and first light freeze of fall for locations across the U.S. and Canada. Simply enter your ZIP or Postal code in the field above to see frost dates for your location (based on the nearest weather station), as well as the length of your growing season based on frost dates.

What are Frost Dates?

A frost date is the average date of the last light freeze in spring or the first light freeze in fall.

The classification of freeze temperatures is based on their effect on plants:

• Light freeze: 29° to 32°F (° to 0°C)—tender plants are killed.
• Moderate freeze: 25° to 28°F (° to °C)—widely destructive to most vegetation.
• Severe freeze: 24°F (°C) and colder—heavy damage to most garden plants.

Note that frost dates are only an estimate based on historical climate data and are not set in stone. The probability of a frost occurring after the spring frost date or before the fall frost date is 30%, which means that there is still a chance of frost occurring before or after the given dates!

Frost is predicted when air temperatures reach 32°F (0°C), but because it is colder closer to the ground, a frost may occur even when air temperatures are just above freezing. Always keep an eye on your local weather forecast and plan to protect tender plants accordingly. Weather, topography, and microclimates may also cause considerable variations in the occurrence of frost in your garden. Learn how to protect plants from frost.

Frost dates are calculated based on data from the NOAA National Centers for Environmental Information.

Wondering when to plant what? Get a head start on gardening with our Planting Calendar, customized to your location!

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