As fall arrives across the United States, leaves will be changing color and painting the landscape in brilliant shades of red, orange and yellow before the white of winter settles in. But the timing and intensity of these fall foliage displays depend heavily on the weather.

Why do leaves change color?

Leaves get their color from pigments, which are produced during different parts of their life cycle. When the leaves are green it is because the sun triggers the leaves to keep creating chlorophyll.

As fall approaches and less sunlight hits the leaves, the production of chlorophyll decreases and existing chlorophyll in the leaves starts to break down, allowing the other pigments to show through instead.

How does weather impact fall colors?

Precipitation amount, temperature and sunlight will all impact how long the leaves stay green, along with how vibrant the other colors become before the leaves start falling off the trees.

Severe drought and frost can reduce color displays and even cause leaves to drop prematurely.

While sunny days help colours develop, overcast conditions can sometimes make colours appear richer to observers by reducing glare.

When looking for fall colors, look for places that have experienced cool, frost-free, clear and dry conditions for the last few days. Soil moisture also plays a factor in the vibrancy of the colors, with moist soil needed during the growing season to help with the color display later in the year. If the soil is too dry during the last weeks of summer, it can cause the colors to lose their vibrancy as well.

When is the best time to see fall colors in the US?

There are several locations in the US that are known as hot spots for travel when it comes to viewing the fall colors. New England, northern Minnesota and parts of the Appalachians and Rockies are popular areas for viewing fall colors.

Image: Fall foliage in Vermont. Source: iStock / para827.

For higher elevations in Colorado through portions of Wyoming and Montana, leaves have already started to change, with their peak colors expected to be between now and the first week of October.

In northern Minnesota, colors may have started the process of changing, but the peak time to travel along Lake Superior will be late-September into early October, with chances further south in Minnesota and Wisconsin being a bit later in October.

Over New England, leaves in higher elevation will start changing soon, with chances for those bright reds, oranges and yellows into early to mid-October. In warmer parts of the US, like the Southeast and Southern Plains, it may take until November to see some color change, which will be past peak for much of the country.

Where can I get local information about fall colors?

Many states known for fall foliage tourism provide updates on their Department of Natural Resources websites, which is usually updated daily. For a longer trip, travelers should also check out long range forecasts for dry, clear conditions and monitor the timing of the first frost.