The Sound of Late Summer: why cicadas make it, and the old folklore surrounding their song

Why are cicadas so loud in August? Learn what cicada sounds mean, why they seem louder on hot days, and whether cicadas can actually predict the weather.

There is a sound that seems to arrive every year just as summer begins leaning toward fall.

It starts as a distant buzz in the trees. Then, on a hot August afternoon, it can suddenly become almost deafening—a rising, vibrating chorus that seems to fill the entire neighborhood.

Cicadas are the soundtrack of late summer.

Across much of the United States, annual cicadas are especially noticeable from July through September, with their numbers and noise often peaking during August. Unlike the famous periodical cicadas that emerge in enormous numbers every 13 or 17 years, annual cicadas appear somewhere every summer.

But why do cicadas make so much noise? Why does the sound seem especially intense when it’s hot? And is there any truth to the old idea that cicadas can predict the weather?

Why Are Cicadas So Loud in August?

The loud cicada sound you hear coming from the trees is mostly about one thing:

Finding a mate.

Male cicadas produce the familiar buzzing call to attract females. They make the sound using specialized structures on their abdomen called tymbals.

Rather than rubbing their wings together like crickets, cicadas rapidly flex these ribbed membranes inward and outward. The movement happens so quickly that the individual clicks blend together into the buzzing, whining, or pulsing sound we associate with summer.

The cicada’s body also acts as a resonating chamber, amplifying the noise considerably. Smithsonian researchers describe male cicadas joining together in large groups called choruses, creating the tremendous wall of sound heard in trees during summer.

So when you hear a tree seemingly “buzzing,” you may actually be listening to dozens of male cicadas calling at once.

Why Do Cicadas Seem Louder When It’s Hot?

If you’ve ever noticed that cicadas become especially noisy during a blazing August afternoon, you aren’t imagining it.

Cicadas are ectothermic, meaning their body temperature and activity are strongly influenced by the temperature around them.

Research has found that temperature can affect several characteristics of cicada songs, including the rate and intensity of their calls. In some species, warmer temperatures are associated with increased calling activity or greater sound power.

That helps explain a familiar summer pattern:

A cool morning may be relatively quiet.

By midafternoon, after the trees and air have warmed, the cicada chorus can become dramatically louder.

This connection between insects and temperature is one reason people have watched—and listened to—bugs for generations as natural weather indicators.

Farmers’ Almanac readers may recognize the same idea from animal weather folklore and our look at animals that can predict the weather.

What Does the Cicada Sound Mean?

Although it may sound like random buzzing to us, cicada calls are a surprisingly sophisticated form of communication.

The loud calls you hear are primarily male mating calls designed to attract females.

Different cicada species also produce distinctly different songs. Some buzz continuously. Others produce pulses, rattles, whistles, or calls that rise and fall.

In fact, scientists can sometimes identify cicada species simply by listening to their songs.

Only the males produce the familiar loud mating calls. Females listen and respond to males of the appropriate species.

So that enormous August chorus isn’t cicadas complaining about the heat.

It is essentially a giant insect singles scene taking place in the treetops.

Why Do Cicadas All Start Calling at Once?

Cicadas frequently call together in groups known as choruses.

When one male begins singing, nearby males may join in until an entire group of trees seems to come alive.

There are several potential advantages to this behavior. Most importantly, a large chorus can help attract females from farther away.

For humans standing underneath it, however, the result can be astonishingly loud.

During enormous periodical cicada emergences, cicada choruses have been reported around 110 to 120 decibels at close range, comparable to extremely loud machinery.

The annual cicadas heard during an ordinary August aren’t usually present in those extraordinary numbers, but a large local chorus can still be remarkably loud.

Are the Cicadas You Hear Every August the 17-Year Cicadas?

Usually, no.

This is a common source of confusion.

The cicadas most Americans hear buzzing every July and August are often called annual cicadas or dog-day cicadas.

That doesn’t necessarily mean each individual cicada completes its entire life cycle in one year. Many spend several years underground as nymphs before emerging.

They are called annual cicadas because some adults emerge every year.

Periodical cicadas are different. Their populations emerge together after spending either 13 or 17 years underground.

Timing is another clue. Penn State notes that annual cicadas commonly emerge from July through September, while periodical cicada broods generally emerge much earlier, during late spring and early summer.

So that familiar August buzz is usually the annual variety—the true soundtrack of the dog days of summer.

Can Cicadas Predict the Weather?

This is where cicadas become especially interesting from an Almanac perspective.

For generations, people have paid attention to insects, birds, animals, plants, clouds, and other features of nature for clues about changing weather.

You can explore many of those traditions in the Farmers’ Almanac collection of weather lore.

But can cicadas actually forecast the weather?

Not in the way a weather forecast can.

There is no good evidence that cicadas know whether a storm is coming next week or whether the upcoming winter will be harsh.

However, cicadas do respond strongly to current environmental conditions, especially temperature.

That means their behavior can tell you something about what is happening outside right now—even if it cannot reliably tell you what will happen days or months from now.

Penn State Extension specifically notes that folklore has sometimes connected cicada singing with the day’s heat, but research does not support using their calls as a reliable temperature-prediction formula.

Do Cicadas Tell You the Temperature?

You may be thinking of another famous insect weather trick.

Crickets can sometimes be used to estimate temperature.

The relationship between cricket chirping and air temperature is so well known that variations of the formula have been passed down for generations.

Cicada calls also change with temperature, but there isn’t a similarly dependable “count the buzzes and calculate the temperature” rule for cicadas.

If you’re interested in natural weather indicators, see our guide to animal weather forecasters.

Do Cicadas Mean Fall Is Coming?

In a sense, they do.

A loud cicada chorus doesn’t mean that cold weather will arrive tomorrow, but its timing is one of nature’s unmistakable seasonal signals.

Annual cicada activity often peaks during August before gradually declining through September and into early autumn.

At the same time, other subtle changes are happening all around us.

The days are getting shorter.

The Sun is setting earlier.

Birds are beginning to gather.

Acorns are falling.

Goldenrod is blooming.

A few leaves may even begin showing their first traces of color.

We’ve collected more of these clues in 10 Signs in Nature That Fall Is Closer Than You Think.

Cicadas belong on that list too.

Their chorus doesn’t announce that summer is over.

It tells us that summer has reached its mature, late-season stage.

What Happens to Cicadas When Summer Ends?

Adult cicadas don’t remain above ground for very long.

After mating, female cicadas use a specialized structure to cut small slits into twigs, where they deposit their eggs.

The eggs eventually hatch, and tiny nymphs drop to the ground. They burrow beneath the soil and begin feeding on fluids associated with plant roots.

There they may remain for years before eventually emerging and beginning the cycle again.

Meanwhile, the adults gradually disappear as late summer gives way to autumn.

One afternoon you suddenly realize something has changed.

The trees are quiet.

Another summer’s cicada chorus is over.

Cicadas: One of Nature’s Signs of Late Summer

Long before weather apps, air conditioners, traffic, and lawn equipment filled our days with noise, generations of people heard the same seasonal chorus coming from the trees.

That’s part of what makes cicadas so remarkable.

Their buzzing isn’t simply background noise.

It is a biological signal, a mating call, a response to summer heat—and one of the most recognizable signs that the seasons are beginning to turn.

So the next time you walk outside on a hot August afternoon and hear that tremendous buzzing overhead, stop and listen.

Hear that? It’s the sound of late summer.

Keep Watching the Signs of the Season

Nature offers plenty of clues that summer is beginning to wind down. See 10 Early Signs of Fall in Nature, find out when the first frost is expected in your area, or explore the Farmers’ Almanac archive of weather folklore and traditional weather signs.