First Alert Weather In-Depth: When can we expect our first frost?

ROCHESTER, N.Y. (WHEC) — We know this time of the year pollen is a big deal, right? Weather, pollen and pollutants, they’re kind of intertwined and we keep track of this kind of thing this time of the year.

This late in the season, the major allergen is weed pollen and in particular, ragweed.

Those who suffer from these kinds of environmental allergies know what I’m talking about, and I get the same kind of thing.

So looking ahead what’s going to remove this from the atmosphere? It could be rain- number one. But number two is if we get a killing frost across the area and we think we have the potential for a killing frost coming up.

Now, this is going to be Thursday night into Friday morning. We think, more than likely, it’s going to be south of Rochester down through the Southern Tier that will end the growing season. It is not unusual to get frost this time of the year.

This is a look at the climatology for the average date for the first frost of the year. Notice that the Southern Tier is in September, but notice that the average date is later in the season as you move closer to Rochester.

Why is that? Well, the warmer waters of Lake Ontario hold up the temperature. So it takes longer and later for the temperature to drop.

Before you know it we’ll be talking about the "S-word".