What Is a Sunshower—and How Can It Rain While the Sun Is Shining?

It’s one of those weather moments that seems like it shouldn’t be possible: rain is falling, but the sun is shining brightly.

This is called a sunshower, and there’s nothing contradictory about it. Rain doesn’t necessarily fall straight down from the cloud directly above you. Wind can carry falling raindrops away from their parent cloud, sometimes far enough that you’re standing under blue sky and sunshine while the rain arrives from somewhere else.

Sunshowers also create some of the best conditions for seeing a rainbow.

What Is a Sunshower?

A sunshower is simply rain falling while the sun is visible and shining.

It often happens when the rain-producing cloud is relatively small or isolated. The cloud may be off to one side of you while the rest of the sky remains clear enough for sunlight to reach the ground.

This is especially common with scattered showers and summertime thunderstorms, when one part of the sky can be dark and rainy while another is bright blue.

How Can It Rain When There Are No Clouds Overhead?

The key is that raindrops don't always land directly beneath the place where they formed. Once a raindrop leaves a cloud, it continues falling through the atmosphere for hundreds or even thousands of feet. During that trip, winds can push it sideways.

In fact, a raindrop can travel a surprisingly long distance from cloud to ground, encountering wind, dry air and changing atmospheric conditions along the way.

If winds at lower levels of the atmosphere are strong enough, rain can drift beyond the visible edge of the cloud that produced it. By the time those drops reach the ground, you may be standing in full sunshine.

From your perspective, it can look as though rain is falling out of a clear blue sky.

How Far Can Rain Travel From a Cloud?

There isn’t one fixed distance because it depends on several factors, including the height of the cloud, the size of the raindrops, wind speed and direction, and how dry the air is below the cloud.

Smaller drops fall more slowly than large ones, giving the wind more time to carry them sideways. Rain falling from a high cloud also has farther to travel, so it can be displaced more before reaching the ground.

This is one reason rainfall can vary surprisingly much across a short distance. Your yard may get wet while a spot a short distance away stays completely dry—or vice versa.

Sometimes the Cloud Is There—You Just Can't See It

Not every sunshower requires rain to travel a great distance.

Sometimes the rain-producing cloud is simply behind you or outside your immediate field of view. Other times, a small shower cloud may occupy only a narrow section of the sky while sunlight streams around its edge.

Because the sun is so bright, our attention naturally goes toward the clear, illuminated part of the sky. The cloud responsible for the rain may be much less obvious.

Why Sunshowers Often Produce Rainbows

A sunshower brings together exactly what a rainbow needs: sunlight and airborne water droplets at the same time.

Sunlight entering a raindrop is refracted, reflected inside the drop, and refracted again as it exits. The different wavelengths of visible light emerge at slightly different angles, separating white sunlight into the familiar colors of a rainbow. You can read more about how rainbows form and why they appear as curved bands of color.

There is one important catch: the sun and the rainbow need to be on opposite sides of you.

If the sun is behind you and rain is falling in front of you, conditions may be just right. When the sun is low in the sky—particularly in the morning or late afternoon—the rainbow can appear especially large and dramatic.

So if you're caught in a sunshower, turn your back to the sun and look toward the rain.

Why Sunshowers Can Feel So Strange

Most of us think of weather as something happening across the entire sky: sunny, cloudy, rainy or clear. In reality, weather can change over remarkably short distances.

A small shower may be dropping rain over only part of a neighborhood. Wind can carry that rain beyond the cloud. At the same time, sunlight can arrive from an entirely different direction without being blocked.

A sunshower is a particularly visible reminder that the weather overhead and the weather reaching the ground aren't always exactly the same thing. And when sunlight, falling rain and your position all line up just right, you may get one of the atmosphere's best bonuses: a rainbow.