Weather Impact: Fall 2024 Preview

Hello, I'm Weather impact chief meteorologist Scott Connell. Welcome to September. September in Saint Louis can mean a lot of things from triple digit heat to an early season first frost. It's a very transitional month as we work our way deeper into fall. Speaking of fall, September 1st is when we begin our journey into meteorological fall, the three months of September, October and November, this is meteorological fall. The autumnal equinox usually falls on a different date each year due to the earth's position this year. That happens to be September 22nd at 743 in the morning with less sunlight, temperatures get cooler while we know that's the trend. How quickly do we get there? Weather impact meteorologist Gary Frank breaks it down for us. I'm weather impacts meteorologist, Gary Frank and welcome to Fall as we continue to work our way toward fall, whether or not by just statistics only or into the equinox, depending on what time you're watching this. I'll tell you what, uh we're gonna continue to go throughout the month and lose a little daylight. We know that, but how quickly does it come? Because as we lose daylight, obviously things start to get cooler, uh, just because that's what happens. Right. The lag of the seasons. But by 729 that's September first by October 1st at 642 we're just under 12 hours of daylight there as we work our way toward that equinox. But as we get towards November 1st, it's six o'clock. We have 10.5 hours or so of daylight and then of course, fall back 457. That's where things change just because we take and shift it. But how does this change our temperature? Let's talk about the temperatures and what we should for the be for the month of September, we know it's still gonna be hot. We've already had temperatures in the forties throughout our area. We haven't had too many hundreds, but it's been warm overnight. So let's look at our historical averages throughout the month of September in Saint Louis. We've hit 100 and four degrees three times in the month of September 5484 and 2011. So it can still get plenty hot, but it can also get cold 32 degrees in 1942. A very early freeze for us, by default, we should expect around three inches of precipitation. And our average temperature high and low combined is about 61 degrees. So it's still gonna be pretty nice. It's still pleasant. And then as we work our way into October still can get hot but that's where we start to get rid of the 100 degree heat. Uh, and then we get only about 94. We'll get plenty of nineties that are possible. We've done it four times 94. At least we've done 90 more than that. But it also can get very cold as October as you would expect is a transitional month for us here in the by state with 21 degrees in 1925. Our precipitation averages just over three inches of rain for the entire month and our temperature average starts to come down as you would expect at about 59 degrees just because we can see those pretty good spreads on hot and cold. And then November, as you would expect is the coldest month statistically in that fall period that we go from where it could still get to 86 we got that 1937 and we'll still get plenty of warm days. But as you would expect, this is the time of the year where we start to see those big stretches where uh 85 degree temperature spread. It's not out of the question as we start to inch up our average precipitation with November being the wettest of the three fall months and our average temperature coming down significantly. So that's the big story for us as we look ahead throughout the entire three month period on some of those averages. Now as it and we looked toward last year, it was really dry last year. So we'll continue to see if we look toward a better fall and have updates throughout the rest of the show. Speaking of last year, many of us can remember how incredibly dry it was. Gary's just showed us where we're supposed to be during the fall season, but we are far from that in many aspects. Now, we managed to receive about 5.85 inches of rain in Saint Louis last year from September through November there. And of course, with less than an inch of that falling in November, that coupled with six days in the nineties really inhibited our fall color in the leaves. Now, this year, not only are we over five inches of precept ahead of last year, we're three inches ahead of where we were last August. Now, do these differences in yearly precept totals leading up to the fall season really make a big difference or have a weather impact. I spoke with Evan Fisher, a meteorologist as well as the owner and founder of explore fall.com to give us some insight on what we can expect for our area this fall season last year, kind of kind of stunk for us to some degree. Um You know, we still obviously are going to see the vibrant colors as you know, but, you know, talk a little bit about what you study about how, you know, temperature is going to impact leaf color um, you know, as we, we start to get warmer and warmer nights, cooler nights, things like that. How does temperature as you see impact leaf color? Yeah. So temperature is really kind of our biggest driver of fall foliage. We do have to wait until the days grow short enough. But once we reach that point in September temperature takes over and those cool nights are really what we're looking for and we want to see, you know, that low color and even peak color emerge out of our forests. Uh depending on your location, you're really there in your area, in the central part of the country, you're looking at October when those nights are truly getting down into the forties and sometimes the thirties and that, you know, mid thirties, low forties is a sweet spot for fall foliage change. Of course, that's all dependent on precipitation and a who a whole host of other variables. But that is the sweet spot. You don't want eighties or nineties in October, those aren't great. That'll delay the delay, the color and actually reduce the brilliance of that color. And you also don't want subfreezing temperatures. It's a, it's a pretty narrow range that we're looking for. Thing for us was the drought stress. You know what we noticed last year as we were in more of a significant drought was, you know, the drought stress from last year really started to shed those leaves early. Can you talk about how uh maybe you're noticing it this year versus last year. And what impact do you think that's going to play on, on some of our fall foliage? Yeah. So last year was really tough across much of the Midwest, central part of the country. Uh that like you mentioned that severe to extreme drought really rocked the trees. Thankfully, we've seen that a debate over the past year and we're going into fall 2024 with basically no drought conditions across Missouri, Illinois. And then there in eastern Kansas is kind of a gradient. Um But hopefully this year, the colors are a lot prettier. We don't expect that early leaf drop like we had last year. We don't expect burned out colors like we had last year. We kind of seem to be right in that middle ground where we wanna be just like we have a narrow range of temperatures that we're looking for. We also have that narrow range of precipitation conditions that we're looking for and it's not overly wet, it's not overly dry. We're just kind of right there and of course, we still have about a month and a half until the colors are changing in that part of the country. Uh And so things can change, but we've gotten through the bulk of the summer. Well, and I think things will progress for a beautiful fall this year. Next question, does it matter when there is a drought season wise like, so if we go run into this, you know, obviously you guys are not quite in the same pattern as we are right now, we're getting a lot more rain. But, you know, as we start to see some of these late season pushes from tropical systems or, you know, we're going into a, a nice two week period where we're barely going to get any rain and we've had a big surplus of rain. Will that start to make a minor or even major changes as we head into the fall season, do you think? Yeah, that's likely to, in, um, that's likely to introduce some minor stress, low end fall fully in stress. And that's almost common that we see that almost every single season there is some stress or whether it's two weeks of good rain followed by two weeks of no rain, more or less it happens in every year. Uh, so I do think you'll see some of that as September approaches, it's, it's often seen in maples, they start to turn color very early. They're, they're quite prone that stress. But the most concerning time frame is generally September. That's where things can be made or broke, made or broken for the season. If you have a drought that lingers into September, that's gonna be a problem. If you have 12 inches of rain in September, that's gonna be a problem. Generally, I'm not too concerned at this point in the, in the season unless it's something like an extreme drought or, or a summer of just nonstop rain as long as you're more or less where you want to be, you know, just neither of those two extremes. You're generally ok right now and we have to wait until September to see if any last second concerns pop up as far as, uh, you know, an early frost or freeze or later contribution. You kind of mentioned temperatures kind of hovering that 35 degree mark. Is it ok when we get, you know, temperatures around freezing or once we get the hard freeze or more, uh multiple nights of uh temperatures around freezing, is that really going to uh start to turn those colors sooner or does that kind of accelerate the process of where we see less, less vibrant colors of those reds and oranges? And we just kind of go from yellow to done basically. Yeah. So right there at 32 you're almost still OK. It's when you're starting to talk about the upper twenties that you really could have some problems. So if you do see a hard freeze, it's likely that the leaves are gonna drop much more quickly and there's a chance that they might may not have time to really flesh out all of those colors that like to see, you know, the reds are really coveted. I know they don't come every year and sometimes that's a result of temperature and whether or not, we get down around that freezing point or below it. Uh, but those upper twenties can be quite dangerous for fall foliage. And that's why you want to stay in the mid to upper thirties. You know, we're looking right now, statistically, it's the third warmest year. Uh, you know, we're the 24th wettest. We were a big difference from last year in terms of moisture and precipitation and soil moisture, which is obviously a big key. Um, you know, based on just that as we, you know, kind of don't talk about uh working throughout the rest of September just yet, you know, is that a positive outlook for us right now? Yeah, I think the color outlook is good. I would not call it the greatest outlook in the world because we've seen that a long duration kind of warmth throughout the year and we've also had a pretty wet summer. But overall, I don't see any reason for a concern on the brilliant side of things. Now, on the timing side of things, all of that warmth, all that summer precipitation at the moment that's really leaning towards um inclining towards a later fall foliage season. So it will be later in October, uh maybe even early November when those best colors are showing up. Evan said they're gonna be doing predictions for the fall season forecast as well, especially in accordance with the changing weather conditions, even though fall foliage or the change in the color of the leaves. Prediction is not an exact science. It may provide you with an idea for the best times to enjoy our fall color and we'll update you on these changing conditions and feature the maps and our weather impact forecast throughout the season. Summer. Ours took a toll, a lot of stress. I mean, it, you know, high temperatures, high humidity and they're trying to take up moisture from the soil and there's not much, I can't say that trees get this way but think of like us having a parched throat, you know, when a dry like they maybe that's what they kind of kind of feel like under dry conditions. I took a very quick walk through forest park and it didn't take long to find a tree struggling with drought stress. Oh yeah, that yes, that is definitely a scorch leave. Let's get a closer look here. This tree is a prime example of what can happen during drought conditions. So this is leaf scorch and what's happened here is the tree has not gotten enough moisture. So it's drying moisture in from its leaves which is then causing crispy edges and that dark brown color something we don't want to see ahead of the fall color season. If we don't get enough moisture, especially going into October, we'll probably see more uh faster leaf drop and also the colors will not be as intense. So we may get a little bit here and there, but not to what we've seen in previous years, think brown and bear who are seeing it in some of our trees. Uh They got a little scorched with that last heat wave we had with the high humidity and temperatures and so a lot of trees have dropped a few leaves uh as a result. And also with the drought, they may be also dropping more leaves now too. So we may not see as much fall color later on. It won't be every tree though some will have had just enough rain or shade to put on a fall show. There will still be some color. Some of our trees are gonna still show that so we can still hope, hope and look forward to a little bit this year, Tracy Henson Bob on her side. Now that we've talked about some of the weather impacts that go into making fall colors bright. Let's look into some of the science that actually goes into why these colors change. Well, the one that we're most familiar with is chlorophyll that obviously keeps the leaves green. But as cooler weather settles in the tree's chlorophyll breaks down leaving other chemicals that cause changing colors like the yellows, the oranges and the reds and well, some of our trees are locally known for producing certain colors brighter than others. Here's a blast from the past from a story I did years ago. Looking back on the specifics of our local trees. Missouri and Illinois have a wide variety of trees that allow us to experience a colorful autumn most years. Let's start with the state tree of Illinois, the white oak. This may be the squirrel's favorite trees with the abundance of acorns this year. Now, these stately trees produce brown to red colors as the leaves change and often will be some of the last drop their leaves. Missouri's state tree is the flowering dogwood, one of first to bloom in the spring and often filled with rich red and maroon color in the fall. Birds enjoy eating the red fruit of the seeds. Another favorite is its cat shaped leaves. The tulip tree not only does it grow large but it too produces and provides flowers in the spring and beautiful yellow leaves. This time of year known for its gum balls, the sweet um tree produces vibrant gold red pink purple leaves, they're very large as well. Now, the sassafras tree have a distinctive smell, especially the bark and the roots. These beautiful trees are loaded with fall color like gold, copper orange, peach and burgundy. The sugar maples are like a tree on fire in the fall. These large trees have leaves that will often turn yellow and then reddish orange. Now finally a couple of sumac now smooth sumac, more of a thicket forming shrub has brilliant purplish red leaves. Now, the fragrant sumac is a cousin of poison ivy with its red burgundy leaves and sometimes purple too. And yes, it is the cousin to poison ivy. So you don't want to touch it from five on your side. I'm meteorologist, Anthony Slaughter. The full splendor of fall is fading from shenandoah to the sierra. As humans turn up the heat through climate change, it's toning down vivid colors and pushing back their peak days even weeks later than before the delay in the onset of fall color is just one of many indicators of climate change and that climate change is progressing. That's also an economic concern. Foliage drives an estimated $1 billion of tourism each fall. They're surprised to see the number of tourists that they've seen so far this season despite the delay in color on the tree. So leaf pepper are a real thing and listen, people come out in droves to New England to leave peep. I don't think climate change will kill fall foliage altogether, but I certainly think it's going to redefine what this even looks like. Leaves often skip the most colorful phase when there is drought and look how widespread that is this year. And then there's wildfire smoke. This graph from climate central shows how much more of it has covered our skies this summer. This is still being researched, but early evidence suggests that wildfire smoke affects leaves sort of like drought does by just turning them brown. I mean, if you think of a leaf like nature's original solar panel it is primarily designed to capture sunlight from above wildfire, smoke, scatters light, think about hazy skies. So it's limiting the amount of direct sunlight that a leaf can get. As humans heat up the planet. It is shifting where certain trees can grow and making them more vulnerable to invasive pests. So nature lovers leaf pepper, this should be reason enough to push for big meaningful climate action as we go further into the fall season. It's not just about the foliage. Our late fall period turns our attention to the first frost and freeze of the season and the end of the growing season. Now, let's first talk about the differences between a frost and a freeze and why sometimes the temperature doesn't have to hit the freezing mark for us to have frost on the ground. A lot of times we see frost form, we have mostly clear skies. Anytime we have cloud cover during the day, we don't get quite as warm, which is what we'd expect. But when we have cloud cover at night, that cloud cover acts like a blanket, an insulator and keep some warmth closer to the surface. When skies are clear at night, the heat of the ground rises and escapes making it easier for frost to form. When we have calm winds. The atmosphere doesn't mix around too much. That allows for a small layer of super cooled air to develop if that layer of air gets above freezing. And there is 100% relative humidity in that process, the water vapor will turn to ice, creating a layer of frost. And this can happen even when the air temperature we show you on TV, or you see on your phone is above 32 degrees. Air temperature is measured around 2 m above the ground surface. And the colder air near the ground allows us to see those lower temperatures. So when do we typically get the first frost and freeze of the season? Well, using the last 30 years as our guide ST Louis has a first average of frost of October 23rd. Let me go ahead and show you that. Here we go. So with this, the earliest we have seen during this time period is October 7th, the latest November 13th, which puts our average somewhere around October 23rd. Now for a freeze, our earliest would be October 7th and our latest would be November 27th, our hard freeze. So this is when our plants go dormant. That would be the earliest on November 1st and the latest being December 9th. Let's talk about Saint Charles here. Our earliest frost typically around September 22nd. Our latest October 30th freeze would be October 2nd. The latest would be November 10th and then that hard freeze falls a little bit later, October 16th and the latest we've seen it is December 3rd. That's an important one, especially for your gardens. You everything needs to be kind of put to bed in the winter time. By the time of that hard freeze for Belleville over in Illinois. September 19th would be our earliest, November 3rd as our latest our freeze for September. Our earliest is September 20th. Our latest is November 10th. That's pretty difficult, especially for some of our growers in the Belleville area like Ecker. You know, our apple harvest, for example, we want to see that freeze. The latest is possible to prolong that apple season there. Our hard freeze would be September 23rd and the latest would be October 25th. So now that we've looked at all the historical averages and everything else that goes into the fall season, what can we expect this year? Well, the climate prediction center has us under a drier than average outlook for these fall months. That's not atypical considering fall is usually our driest season anyway. And La Nina is beginning and we also have warmer than average conditions expected. That also isn't surprising because we've been pretty warm for the last couple of years and LA Nina tends to produce warmer than average conditions and usually drier too. So we become the beneficiary of warmer and drier conditions. Now that can change and can do so pretty quickly. You know, the Atlantic tropical season is underway and we're reaching towards the peak of that from September into the beginning of October. And so we could have tropical activity in the Gulf of Mexico record temperatures for sea surface temperatures down that way that could fuel a strong storm. If a tropical low comes our way, that would definitely bring us potentially some heavy rainfall and also lower our temperatures. You can bet the weather impact team will be tracking this for you throughout the season and bring you the latest changes in this forecast.