ROCHESTER, N.Y. — Here is a timely question: When does our growing season come to an end? But a better question might be when do we see our first frost or freeze? If that crystallization does materialize, that will effectively kill any outside plants.

History shows that the average date for first frost across New York State will vary from north to south for specific communities. The southern tier valleys have already had a frost, but not here in Rochester. Our average date for the chill is usually the middle of October. It is a month later due to our proximity to the city and Lake Ontario. As we get later in the season, these two geographic points usually hold onto the heat a little longer. Recently our computer modeling shows that Wednesday morning we is a higher probability for frost south of Routes 5 and 20.  However, that same computer model shows there could be better a slightly better chance of frost closer to Rochester for Thursday morning.

What is the meteorological process for the formation of frost? Remember, that we measure the temperature at about five feet above the ground. But the colder air is heavier and more dense has a greater chance of sinking closer to the surface of the Earth. So even if the thermometer is measuring above freezing, at the surface it could be below freezing. Any moisture molecules that come in contact with a frozen surface, such as grass or a car, that is the point of frost formation. The favorable weather conditions for frost this time of the year is clear skies, light winds, and a little bit of moisture near the surface.

If you have any flowers left over from the summer season, it is recommended that you either cover them or bring them inside. On the other hand, if you are tired of mowing the lawn this could frost could be a good thing.