Weather Blog: Fall foliage forecast and timing

Weather Blog

What can you expect for fall foliage viewing this year across Northwest Arkansas and the River Valley?

With astronomical fall arriving last week, many of you are starting to wonder what the fall foliage and colors be like this year? The short answer is the fall colors are NOT EXPECTED to be very vibrant and colorful. Most of the color will also be patchy at best.

Here is an animation of the climatological peaks of fall foliage across the United States.

Why Will the Colors be Patchy and not Vibrant This Year?

The main obstacles to us seeing beautiful fall foliage this year is the lack of rain that we have had during the late summer months (July-August) and the lack of cool overnight temperatures (less than 40°F) at the present. Both of these combinations paint a dismal picture for those of you wanting to see some widespread beautiful fall colors.

Precipitation Departures from Normal for Northwest Arkansas

This is illustrated by looking at the precipitation departure from normal for the past 60 to 90 days. 60 days would place us back in late July and 90 days place us back in late June.

Starting with the 30-day departure, we can see most of Northwest Arkansas saw a deficit of 2-3 inches of precipitation. Parts of southern Washington Co also saw up to 4 inches of a deficit including areas near Devil’s Den State Park. Some parts of the higher terrain in Madison, Boone, and Newton counties saw a smaller deficit due to the terrain-driven shower and thunderstorm activity.

Moving onto the 60-day departures we can see that there are still widespread precipitation deficits of 2-4 inches across most of Northwest Arkansas. Washington county seemed to see the greatest deficit of rainfall for a 60-day departure.

Looking at 90-day departures the picture of rainfall deficit doesn’t get much better for Northwest Arkansas. Most areas are still seeing widespread 2-4 inch deficits.

The same data across the River Valley does not look any better. The better foliage across the River Valley tends to be located in the Southern Boston Mountains and the Ouachita Mountains.

The 30-day departure shows much of Crawford and Le Flore counties with precipitation deficits of at least 3 inches or more! These areas of deficit are located across most of the Southern Boston Mtns and the Ouachitas.

The 60-day departure shows again, widespread rainfall deficits of 4-6 inches. Some locations in Sequoyah and Johnson counties saw a small surplus of 1-2 inches of rain, but most of the River Valley is well below average for normal rainfall.

Going back 90-days we can see that many portions of the River Valley actually saw some decent above average amounts of precipitation. Parts of Franklin county saw anywhere from 2-8 inches above average! Even though many places in the River Valley saw above-average rainfall over the last 90 days, the deficit has really taken over and dried out many of the trees.

Why Does Rainfall Matter so Much to Fall Foliage?

It was a very dry end to the summer and the start of our fall. Most of our yards are brown and we are seeing low lake levels on Beaver Lake. So it has been dry, but why is the lack of rain so important to Autumn colors? Rain is important to sustaining the green leaves on the tree as long as possible in order to reach the cooler overnight temperatures typically experienced in the fall months.

With the extremely dry conditions experienced over the last few months, many of the leaves of the trees are already starting to fall to the ground brown and dead. The trees must conserve water to stay alive so the first thing to be cut off from the flow of water is the leaves. Without water to keep them alive, the leaves dry out, turn brown, die, and fall off the trees.

Why are Cold Temperatures Needed for Vibrant Color?

Temperatures below 40 degrees F allow the sugars to be trapped in the leaves. As the fall days get shorter and shorter, the production of chlorophyll slows down and eventually stops. Leaves only appear green due to the presence and production of chlorophyll. Once the production of this compound stops, the leaves start to take on their true colors based on the compounds found inside them. To see what type of compound the colors you like see the graphic below.

Peak Fall Foliage Forecast Times

According to smokymountains.com, the Ozark Mountain’s (includes our region) fall foliage will peak around October 18th. Make sure to get all leaf-peeping in before the end of the month of October.

Keep in mind this map is based on the climatological peaks of fall color across the United States. This forecast is subject to change based on localized weather patterns such as wind storms that can shed trees of their leaves early especially if they are dry.

All of this being said, there could possibly be patches of color briefly if we see cooler temperatures over the next few weeks. You will just have to search for the areas of color since it won’t be widespread. If you do locate some vibrant fall colors around the area please send us your photos we would LOVE to see them!

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

Weather News

More Weather

Latest Video

Weather Visits

DON'T MISS

More Don't Miss

Trending Stories

Follow KNWA & FOX24 on Facebook

get the app

News App

Weather App

Follow @KNWAFOX24 on Twitter

Trending Stories

Mega Millions & Powerball Numbers