The northern lights may return to the night sky over Canada and parts of the United States tonight, forecasters said.

An eruption from the sun, known as a coronal mass ejection, occurred over the weekend and is expected to impact the Earth’s magnetic field late Monday into early Tuesday, NOAA’s Space Weather Prediction Center said. When it happens, it will set off a colorful display of the aurora borealis.

People in 18 U.S. states could see the green or red glow of the aurora in the sky Monday night.

According to weather forecasters, the upcoming light show is not expected to be as significant as those seen across the sky in 2024, but for some, it will be one of the best opportunities to see the lights since the spring.

What are the northern lights?

Auroras, displays known as the northern and southern lights, are commonly visible near the poles, where charged particles from the sun interact with Earth’s atmosphere.

Every 11 years, its poles swap places, causing magnetic twists and tangles along the way. The sun’s active spurt is expected to last at least through the end of this year.

In spring 2024, the strongest geomagnetic storm in two decades slammed Earth, producing spectacular light displays across the Northern Hemisphere. Last fall, a powerful solar storm produced dancing lights far from the Arctic Circle.

Where will the auroras be visible tonight?

According to NOAA’s Kp index forecast, the geomagnetic storm is expected to peak somewhere between 2 a.m. and 5 a.m. ET on Tuesday.

Based on NOAA’s prediction map, the northern lights could be visible in:

1. Alaska
2. Montana
3. North Dakota
4. Minnesota
5. Wisconsin
6. Michigan
7. Maine
8. South Dakota
9. Vermont
10. New Hampshire
11. Idaho
12. Washington
13. Oregon
14. New York
15. Wyoming
16. Iowa
17. Nebraska
18. Illinois

How to see auroras

Consider aurora-watching in a quiet, dark area away from city lights. Experts recommend skygazing from a local or national park. And check the weather forecast because clouds can cover up the spectacle entirely.