ROANOKE, Va – In just about two months, leaves across parts of our region will start to turn color. While there are still 61 days of summer left, the weather we have seen over the past couple of months and the weather we are seeing now play a big role in how beautiful the fall color will be.
The two big players weather wise that determine how vibrant the color will be are temperature and moisture. If the soil is dry leading up to autumn, the tree could be stressed and have dull color before shedding its leaves quickly.
A dry summer could also delay the onset of fall color, which is what we saw last year.
It's no secret that 2017 was a down year for fall color. Last growing season, typically starting in late March or early April and ending in late October, started off wet and then turned very dry from July through October.
This time last year, 7 percent of Virginia was considered "Abnormally Dry" by the USGS.
This year, only .57 percent of the state met that distinction and none of that is in our immediate area, so there are some positives early on in the game. The current drought monitor is below.
That dry spell in late September of last year no doubt had a negative impact on the color across the region. It also didn't help that last September was warmer than normal and October was much warmer than normal.
The temperature may even be more important to getting the spectacular fall color. Sunny, warm days followed by crisp, above-freezing nights in fall is just what the doctor ordered to get the fall color to explode. This temperature combination produces sugar in the leaf and allows the leaf to retain that sugar.
The color in 2016 was better than 2017, but still wasn't very vibrant. Every month from May to October had above normal rainfall, but September was 5.5 degrees above normal and October was more than 4 degrees above. For a spectacular fall, near-perfect conditions are needed on both the temperature and moisture fronts.
For July, Roanoke currently stands about one inch below normal in the moisture department. In short, the rain we saw over the weekend and the wet pattern we are staying in for the fourth week of July will no doubt help the cause for good fall color, but we can't shut off the faucet in August and September. In addition to that, we would be rooting for cooler nights in late September and through the month of October.
For the cherry on top, we wouldn't want much rain or wind in October so those leaves don't get blown off by the wind or ripped off by heavy rain.
Stay tuned for more updates on the fall color as we get closer to the season.
WIND RAIN shorter time scale.