10 Early Signs of Fall in Nature

The calendar may still say summer, but nature doesn’t always seem to follow the calendar.

Maybe acorns are suddenly pounding the roof. Squirrels are racing around the yard with their mouths full. A maple down the road has a suspicious patch of red, or birds that spent the summer scattered around the neighborhood are suddenly gathering in large groups.

It’s enough to make you wonder: Is fall coming early this year?

The official start of autumn is marked by the fall equinox, while meteorologists consider September 1 the start of meteorological fall. But the natural transition between summer and autumn is much less tidy. Plants and animals respond to changing daylight, temperatures, rainfall, food supplies, and other environmental cues.

For generations, farmers and other close observers of nature also watched these seasonal changes for clues about the weather ahead. Some became the weather lore and natural forecasting traditions we still share today.

So, is nature trying to tell you that autumn is arriving ahead of schedule? Look for these 10 early signs of fall.

1. Acorns Are Suddenly Everywhere

Thump. Roll. Crunch.

Few sounds announce late summer quite like acorns hitting the roof, bouncing off the deck, and collecting across the lawn.

Oak trees don’t produce the same number of acorns every year. Some years bring especially large crops, commonly called mast years. The University of Minnesota Extension notes, for example, that northern red oaks can produce good acorn crops at intervals of roughly two to five years. Learn more about how oak forests produce and spread acorns.

Old weather lore has a different interpretation. A bumper crop of ripe acorns has long been considered a warning that a cold or snowy winter lies ahead. You may have even heard some variation of:

“Many acorns, much snow.”

There isn’t good evidence that an oak tree can forecast the coming winter, but a sudden abundance of falling acorns is certainly one of the classic sights of the approaching season. Farmers’ Almanac has more on what falling green and brown acorns can mean.

2. Squirrels Look Like They’re Working Overtime

Are the squirrels in your yard suddenly behaving as if the grocery store is about to close for six months?

Late summer and fall bring plenty of nut-gathering activity. Squirrels collect and cache acorns and other foods, sometimes burying them individually across surprisingly large areas.

According to old-fashioned weather lore, squirrels that begin gathering nuts unusually early are preparing for a particularly cold winter.

The reality is more complicated. Their behavior is strongly influenced by the availability of food, including the size of that year’s acorn and nut crop. Even Farmers’ Almanac’s traditional signs of a hard winter are best enjoyed as folklore rather than foolproof forecasts.

Still, when squirrels suddenly become the busiest residents of the neighborhood, fall rarely feels far away.

3. Leaves Begin Changing Earlier Than Expected

A bright red branch on an otherwise green maple is enough to stop any fall lover in their tracks.

As the growing season winds down, deciduous trees begin breaking down chlorophyll, allowing other pigments to become visible. The result is the familiar yellow, orange, red, and purple show of autumn.

You can read more about why leaves change color and check expected fall foliage dates and destinations on Farmers’ Almanac.

But an early splash of color does not necessarily mean an early fall.

Drought, heat, insects, disease, and other stresses can cause trees to discolor or shed leaves prematurely. The U.S. Forest Service explains the science behind fall color, including the importance of weather and environmental conditions.

A good rule of thumb: One stressed tree turning brown early is probably not predicting autumn. Numerous healthy trees beginning their normal color change is a much more interesting seasonal clue.

4. Birds Begin Gathering in Bigger Flocks

Take a look at telephone wires, farm fields, lakes, and open skies.

Bird behavior can change noticeably as summer winds down. Some species begin gathering in larger groups, while migratory birds start preparing for journeys that can cover hundreds or even thousands of miles.

It’s easy to understand why generations before us viewed changing bird behavior as a natural seasonal calendar.

Migration timing varies by species and can be influenced by day length, weather, food availability, geography, and local conditions, according to the U.S. Fish and Wildlife Service.

So if your quiet summer sky suddenly seems much busier, you may be witnessing one of autumn’s first great movements.

5. The Evening Insect Chorus Begins to Change

Late summer has a soundtrack all its own.

Crickets, katydids, cicadas, and other insects fill warm evenings with chirps, buzzes, and trills. But as nights gradually cool, that familiar summer chorus begins to change.

Crickets are especially interesting because their chirping rate varies with temperature. As temperatures rise, certain crickets chirp faster; as temperatures fall, the rate slows. This relationship inspired Dolbear’s Law, which uses cricket chirps to estimate air temperature.

That bit of science may help explain why crickets became such a popular part of old-fashioned weather lore. Farmers’ Almanac explores the connection in its look at America’s old weather sayings and the science behind them.

When your summer evenings suddenly sound a little quieter—or the chirping seems slower—cooler nights may already be arriving.

6. Spider Webs Suddenly Seem to Be Everywhere

You leave the house one cool morning and discover that somebody has decorated the entire yard with spider webs.

Sometimes including one directly across the path to the mailbox.

Many spiders have been around all summer, but certain species become especially noticeable during late summer and autumn as they reach maturity and build large webs.

Penn State Extension describes spider webs as one of nature’s seasonal autumn decorations and specifically recommends looking for them as the growing season slows. See its guide to fall spider webs here.

Cool, dewy mornings make them even more spectacular, outlining every strand with tiny droplets of water.

Large or abundant spider webs have also earned a place in winter weather folklore, although spiders are responding to their own life cycles and present conditions—not reading a long-range forecast.

Want to know who built that giant wheel-shaped web in your garden? Meet the orb-weaver spiders commonly seen in gardens and fields.

7. Monarch Butterflies Start Heading South

One of the most spectacular signs of fall may weigh less than a paperclip.

Each fall, monarch butterflies begin their remarkable migration toward overwintering grounds. Eastern monarchs can travel enormous distances from the United States and Canada toward central Mexico.

According to Monarch Joint Venture, eastern monarchs can travel as far as about 3,000 miles during fall migration.

In late summer, you may notice monarchs feeding heavily on nectar-producing flowers as they prepare for their southward journey. Goldenrod, asters, and other late-blooming plants can provide important fall nectar sources.

Farmers’ Almanac has more fascinating monarch butterfly facts and ways to help monarchs.

When monarchs are on the move, summer’s days are numbered.

8. Mornings Become Cooler—and Dewier

There’s a particular kind of late-summer morning that feels like autumn even before you look at the thermometer.

The air is cool. The grass is soaked with dew. Maybe a little mist hangs over the field.

As nights lengthen and surfaces have more time to cool, conditions can become favorable for dew formation. This is one reason heavy morning dew becomes such a familiar part of late summer and early fall.

And naturally, there’s weather lore for that, too:

“When the dew is on the grass, rain will never come to pass.”

The saying isn’t a perfect forecast, but it contains a kernel of observational wisdom: clear, relatively calm overnight conditions can favor dew formation.

When those cool, wet mornings begin arriving more frequently, the landscape can start feeling autumnal long before the first frost.

Speaking of frost, you can check the average first frost date for your area before cold weather arrives.

9. Goldenrod and Asters Take Over the Roadsides

Trees aren’t the only plants that can tell you where you are in the seasonal cycle.

Look down.

Goldenrod begins lighting up fields and roadsides with masses of yellow flowers in late summer and into fall. Asters add their familiar purples, blues, pinks, and whites as the season progresses.

These late bloomers are also valuable to insects searching for food near the end of the growing season.

Farmers’ Almanac notes that goldenrod blooms from late summer through fall and attracts beneficial insects. Despite its reputation, goldenrod is generally not the plant responsible for most fall hay-fever misery; its pollen is relatively heavy and is carried primarily by insects.

When roadside greens suddenly turn gold and purple, nature’s fall decorating committee has officially arrived.

10. Woolly Bear Caterpillars Start Crossing Your Path

Few creatures inspire more autumn weather folklore than the humble woolly bear caterpillar.

According to tradition, the caterpillar’s rusty-brown and black bands can predict the severity of the coming winter. A wide brown middle band is said to mean a mild winter, while wider black bands supposedly warn of harsher conditions.

It’s one of America’s most beloved pieces of winter folklore.

It’s also not a reliable forecast.

A woolly bear’s appearance is affected by biological factors such as age and development, rather than being a coded report on the winter ahead. Farmers’ Almanac explores both sides of the tradition in Can Woolly Bear Caterpillars Predict Winter?.

Science aside, spotting the first woolly bear of the season has a way of making autumn feel official.

So, Can Nature Really Tell You Fall Is Coming Early?

Yes—and no.

Nature can tell us a great deal about what is happening right now.

Trees respond to daylight, temperature, water, and stress. Birds respond to seasonal cues, food supplies, and weather. Insects follow life cycles that change with temperature and daylight. Flowers bloom according to their own biological clocks and local growing conditions.

What nature usually can’t do is provide a simple long-range forecast.

A bumper crop of acorns doesn’t guarantee snow. A busy squirrel isn’t necessarily preparing for a blizzard. And a black woolly bear isn’t a substitute for a meteorologist.

That’s what makes traditional weather lore so much fun: it mixes generations of close observation with stories and sayings passed down over time.

The trick is to look for patterns rather than a single sign.

If the mornings are getting cooler, birds are gathering, monarchs are moving south, goldenrod is blooming, crickets are slowing down, and healthy trees are beginning to change color, you’re not imagining things.

Fall is on its way.

Keep Your Own Fall Nature Calendar

Want to find out whether fall really does arrive early where you live?

Become a seasonal detective.

Write down the date you notice your first changing maple. Record when ripe acorns begin falling heavily, when monarchs pass through, when large bird flocks appear, when you see your first woolly bear, and when goldenrod reaches full bloom.

Then add the date of your first frost.

Do it for several years and you’ll create something surprisingly valuable: your own local almanac.

You may discover that certain events appear almost like clockwork, while others shift by days or even weeks depending on that year’s weather.

And that kind of patient observation is how people learned to read the seasons long before weather apps existed.

What’s the first sign of fall where you live? Tell us what you’re seeing in your backyard!