The northern lights may be visible overnight from up to 10 northern U.S. states on Thursday, Aug. 20, into Friday, Aug. 21, according to a forecast by space weather experts at the National Oceanic and Atmospheric Administration.

NOAA is predicting a Kp index of four out of nine, meaning the aurora could be visible further south than is typical, though regions at high latitudes are far more likely to see a display.

Northern Lights Tonight: Forecast

The northern lights are caused by the solar wind, a constant stream of charged particles flowing from the sun that interacts with Earth’s magnetic field. While most are deflected, some particles spiral along magnetic field lines toward the poles and collide with oxygen and nitrogen atoms high in the atmosphere. These collisions excite the gases, causing them to release energy as shimmering light.

In this case, the solar wind is made more potent by what space weather forecasters call a coronal hole high-speed stream. A coronal hole is a region on the sun where magnetic field lines open into space, allowing a faster stream of solar wind to escape. When this high-speed stream reaches Earth, it can disturb our planet’s magnetic field. “The geomagnetic field is likely to reach active levels over August 20-22 during the waning phase of the CH HSS,” reads a forecast discussion from NOAA.

Northern Lights Forecast: Where And When

U.S. states that may see aurora include northerly parts Washington, Idaho, Montana, North Dakota, South Dakota, Minnesota, Wisconsin, Michigan and Maine, and southerly parts of Alaska.

To check visibility in real time, use NOAA’s 30-minute aurora forecast , or download apps such as Aurora Now, My Aurora Forecast or Glendale Aurora for up-to-the-minute alerts and live solar wind data.

Northern Lights Forecast: Interplanetary Magnetic Field

Aurora-chasers frequently use the Kp index to predict the intensity of a geomagnetic storm, but for aurora displays, the interplanetary magnetic field’s Bz component is more important (you’ll find it in some of the above apps and on SpaceWeatherLive.com ). Bz determines how easily solar energy enters Earth’s magnetosphere. When Bz points north, Earth’s field resists it; when Bz swings south, the two fields connect, allowing plasma to stream in. A sustained southward Bz of −5 nT or stronger usually signals an imminent display of aurora.

Northern Lights Forecast: How To Photograph Aurora

A mirrorless or DSLR camera is ideal (ISO 1600, 2-10 seconds, f2.8), though newer smartphones are increasingly capable of stunning results. If your smartphone has a Night Mode or Pro Mode , you can capture a beautiful aurora photo with these steps:

  • Use your main lens, not the ultra-wide, for sharper results.
  • Stabilize the camera using a tripod or rest it on a firm surface such as a car roof, wall, or post.
  • Shoot in RAW format if available, as it makes post-editing easier.
  • Expect long exposures between five and ten seconds. Even faint glows that look grayish to the eye often appear vividly green, purple or red in photos.

Northern Lights: Avoiding Light Pollution

Urban glow is the aurora’s worst enemy. To escape it, drive 30–60 minutes from city centers or use light-pollution maps to locate darker skies. Even a modest reduction in brightness can reveal auroral structure invisible under urban haze. A handy way to locate a dark place is the Dark Sky Place Finder and a light pollution map .

Shield stray car lights and avoid using bright flashlights once you arrive. Red headlamps preserve night vision and courtesy to others. Dark-sky parks and lakeshores north of cities often make excellent viewing spots. The rule is simple: the darker the northern sky, the more vibrant the display — even during moderate geomagnetic storms.

Wishing you clear skies and wide eyes.