ROCHESTER, N.Y. (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 near to 32 degrees—or even below, if only briefly. Because a hard freeze kills the growing season, it’s also called a killing freeze. The common threshold is 28 degrees, but anywhere under 32 degrees, for a long enough period of time, can also be a killing freeze.
According to the Nation Weather Service in Western New York, several counties have already seen their growing season end. As of September 22, hard freezes have 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 degrees, but a sustained cold blast let overnight lows drop below freezing for hours.
Counties with a blue X saw their growing season end early. Most of these areas traditionally mark the end of growing season on October 15. Around Rochester, the growing season continues despite frost reported. Their 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 spring. In terms of hearty plants, there is an impressive variance in New York of average minimum temperatures:
The growing season is slowly evolving because of climate change. Since the atmosphere is slowly warming, the growing season is slightly extended. On average, growing season is starting a few days earlier and lasting a bit longer. These are trends over several years and that demonstrate 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.