The northern lights may be visible overnight from northern U.S. states on tates on Wednesday, April 29, into Thursday, April 30, according to a forecast by space weather experts at the National Oceanic and Atmospheric Administration. The forecast is for a possible G1 geomagnetic storm.

Northern Lights Tonight: Where And When

A G1-class geomagnetic storm could see aurora visible on the northern horizon from around 10 northern U.S. states and Canada. U.S. states with the best chance include Alaska and (northerly parts of) Washington, Idaho, Montana, North Dakota, South Dakota, Minnesota, Wisconsin, Michigan and Maine.

If a G2 geomagnetic storm develops, states farther south may also see aurora, including Oregon, Wyoming, Nebraska, Iowa, Illinois, Indiana, Ohio, New York, Vermont and New Hampshire.

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 Alert: Solar Wind

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, colliding 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 a high-speed blast of solar wind coming from a hole in the sun’s corona (outer atmosphere).

Northern Lights Tonight: Forecast

“An increase to unsettled to active levels, with a chance for G1 (Minor) storming, is expected on 29-30 Apr with the onset of a negative polarity CH HSS, stated NOAA in a forecast . “Unsettled levels are expected on 01 May as HSS activity persists..”

That negative polarity is important. Aurora-chasers frequently use the Kp index to predict the intensity of a geomagnetic storm. Still, 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 (positive), Earth’s field resists it; when Bz swings south (negative), 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

The new moon makes this potentially a great opportunity to capture long-exposure aurora photography on the northern horizon. 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.

Wishing you clear skies and wide eyes.