Growing season defined: Killing freeze has arrived, for some


FILE – In this July 11, 2018, file photo, a field of corn grows in front of an old windmill in Pacific Junction, Iowa. The federal government said Friday, Sept. 18, 2020, it would give farmers an additional $14 billion to compensate them for the difficulties they’ve experienced selling their crops, milk and meat because of the coronavirus pandemic. (AP Photo/Nati Harnik, File )

ROCHESTER, NY (WROC) — The growing season is simply defined as the period in which food can be planted. More specifically it is the time between the last hard freeze in the spring and the first hard freeze in the fall.

The 2020 season is coming to an end this week for certain areas as they hit a hard freeze much earlier than the climatological average.

A frost occurs as temperatures drop to near 32° or even drop below it for a brief period of time. A hard freeze is what kills the growing season and is aptly named a killing freeze. The common threshold is 28°, but if temperatures are below 32° for a long period of time, that can also be a killing freeze.

Here are the counties locally that have seen their growing season end, according to the NWS Buffalo Office:

As of September 22, 2020, hard freezes have already hit Cattaraugus, Allegany, and Jefferson Counties as well as others along the Southern Tier. Overnight lows this time of year average much closer to 50°, but a sustained cold blast has been able to allow overnight lows to drop below the freezing mark for hours.

Counties with a blue X saw their growing season end early. Most of these areas mark the end of their growing season on October 15. Around Rochester, the growing season continues despite frost reported. The season ends on October 25, or until there is a killing freeze.

Once the growing season ends, the NWS stops issuing frost advisories and freeze warnings until the spring of 2021. In terms of hearty plants, there is an impressive variance in New York State of average minimum temperatures, as seen by the map below.

The growing season is slowly evolving because of climate change. Since the atmosphere is slowly warming, the growing season is slightly extended. Not only is the growing season starting, on average, a few days earlier, but it is lasting a bit longer. It is important to remember that these are trends over several years and we will still see annual variation. There may be a climate signal that shows the chance for more variance in weather. That could come in the form of a warm stretch in early spring outside the growing season followed by a hard freeze that can damage crops.

You can learn more information on frost and freeze here.


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