Northern lights could return to the northern horizon of parts of the U.S. and Canada after dark on Friday, Oct. 2, as a solar eruption heads toward Earth and may trigger minor G1-class geomagnetic storm conditions.

Space weather experts at NOAA forecast a coronal mass ejection that left the sun on Monday, Sept. 28, to reach Earth overnight on Thursday, Oct. 2 . However, NOAA’s latest forecast has shifted the anticipated peak several hours later.

The CME — a cloud of magnetic fields and charged particles from the sun — is expected to deliver a glancing blow rather than a direct hit. However, it could still produce enough geomagnetic activity to trigger auroral displays across northern North America as darkness falls.

If aurora reaches the northern U.S., a smartphone camera may detect faint colors that are difficult to see with the naked eye.

Northern Lights Forecast For Friday, Oct. 2

The key period for aurora watchers in North America is expected to be just after dark in eastern regions on Friday evening, depending on the CME’s exact arrival time. “G1 (Minor) storm levels are likely following the anticipated arrival of the 28 Sep CME,” said NOAA about Oct. 2. It also forecast periods of active conditions on Oct. 3-4, thanks to a stream of fast-moving solar wind flowing from open magnetic field regions on the sun.

According to the UK Met Office , “A coronal mass ejection from 28 Sep is likely to give Earth a glancing blow in coming hours. A further coronal mass ejection from 30 Sep is likely to miss Earth with a small chance of minor shock influences on Day 2 (03 Oct).”

Where Will The Northern Lights Be Visible In The U.S. And Canada?

Conditions are good for aurora watching on Friday. The moon is a waning gibbous approaching last quarter, but it doesn’t rise until late evening, creating a useful dark-sky window during the first part of NOAA’s predicted G1 period.

If G1 conditions do develop, Alaska and states across the northern tier of the contiguous U.S. (Washington, Idaho, Montana, North Dakota, South Dakota, Minnesota, Wisconsin, Michigan, Maine, Vermont and New Hampshire) could have opportunities to see or photograph aurora, particularly from dark locations near the Canadian border.

Cosmik has live aurora odds for all U.S. states and 552 cities, updated from NOAA’s data, so you can check whether your location may see aurora.

How To See The Northern Lights In The U.S. And Canada

A G1 forecast does not guarantee the northern lights will appear from any particular location, and apps such as Aurora Now, My Aurora Forecast or Glendale Aurora should be used for up-to-the-minute alerts and live solar wind data. The orientation of the interplanetary magnetic field — measured as Bz — will matter once the CME reaches Earth. A sustained southward Bz can favor stronger coupling between the solar wind and Earth’s magnetic field, increasing the potential for auroral activity to be seen farther south than expected. If Bz remains northward, however, the resulting display may be weak or restricted to higher latitudes.

Skywatchers hoping to witness aurora should head to a dark location with unobstructed views of the northern horizon. In addition to the orientation of the interplanetary magnetic field, aurora visibility will ultimately depend on solar wind strength, cloud cover and light pollution.

Wishing you clear skies and wide eyes.