While the astronomical start of fall is about 10 days away, meteorological fall started on September 1 and that means that the fall colors are close behind. Have you ever wondered about the date that leaves begin to change? What about the best time to see those fall colors? Well, today we will learn about the how fast the leaves change during the fall months.
First, where are we now?
It is important to see where the fall colors are right now before talking about where they are going in the future. The first two weeks of September are uneventful as far as the fall foliage goes. In the last week, there have only been minimal changes in the leaf color over parts of the north central United States and the northeast. You can view the leaf changes for September 5-today below.
How will the leaves change from here?
The change in fall colors from this point will be dramatic. The average high temperature from the beginning of September to the end of September in Youngstown drops from around 80 degrees to less than 70 degrees.
The cooler nights cause trees to slow down the process of photosynthesis which results in less chlorophyll (the chemical that makes leaves green). Reduced chlorophyll concentrations in leaves is the reason for the change in color.
When will the peak of fall colors occur in Ohio?
The cooler temperatures in late September and early October will result in the peak of fall foliage in northeastern Ohio and western Pennsylvania during the third or fourth week of October. The map below shows the predicted dates for the peak of fall foliage across Ohio.
The predicted peak in fall foliage for the rest of the United States is shown below. Obviously, areas further to the north see a quicker change in leaf color due to colder temperatures. There are some areas south of the Ohio River that do not see a peak in fall foliage until after November 14.
How does weather affect the changing in the leaves?
There are a number of factors that affect when the leaves change during the fall. These factors can combine to significantly change when the peak of fall foliage occurs.
Temperature: The most obvious factor that can affect the time that leaf color change occurs is temperature. If there is an abnormally cold fall then the peak in fall foliage can occur sooner and the opposite is true if there is a hot fall.
Moisture: The other main variable that affects the leaves is soil moisture. If there are drought conditions during the late summer and fall months then this can delay the onset of leaf change and also cause it to be less colorful.
Thankfully, the temperature has been right around average and the soil moisture is in good shape after a couple of rainy weeks. The fall colors will be here soon!