A potentially stronger round of northern lights could be on the way overnight on Tuesday, Sept. 8, into Wednesday, Sept. 9, as several eruptions from the sun approach Earth.

Multiple coronal mass ejections that left the sun on Sept. 5 and 6 could reach Earth late Tuesday or early Wednesday, potentially combining with an already elevated solar wind to trigger geomagnetic storms.

Forecasts differ on how strong the resulting storm could become. NOAA currently forecasts G1 (Minor) geomagnetic storm conditions, while the UK Met Office says there is a chance of G2 (Moderate) storming as up to three CMEs interact with Earth. A G2 storm could potentially push the aurora into parts of around 20 U.S. states.

The timing remains uncertain, but the Met Office says the peak risk is centered around midnight UTC on Sept. 9 — potentially earlier than previous forecasts suggested. That’s around 8 p.m. EDT/7 p.m. CDT/6 p.m. MDT/5 p.m. PDT on Sept. 8.

Multiple CMEs Could Reach Earth

Conditions are already beginning to change near Earth. According to the Met Office, Earth has connected with a stream of faster solar wind flowing from a coronal hole on the sun, which could by itself produce a chance of G1 geomagnetic storm conditions.

The more significant uncertainty comes next. Up to three CMEs could interact with Earth from later Tuesday into Wednesday after leaving the sun on Sept. 5 and 6. The Met Office says these eruptions produce a broad chance of G2 geomagnetic storming across Sept. 8-9.

However, NOAA’s latest forecast is more conservative, predicting a maximum Kp index of 5 — equivalent to a G1 geomagnetic storm — through Sept. 10.

Northern Lights Forecast Tuesday Night

If G1 geomagnetic storm conditions develop, aurora could become visible from dark locations across parts of the northern U.S., including Alaska and parts of North Dakota, Maine, Minnesota, Vermont, Montana, New Hampshire, South Dakota, Washington, Wisconsin and Michigan.

The UK Met Office’s stronger G2 scenario could push the aurora farther south, potentially bringing it within reach of observers in Oregon, Wyoming, Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania and New York.

Exactly how far south the aurora reaches will depend not simply on the strength of the incoming solar wind, but particularly on the orientation of its magnetic field when it reaches Earth. Skywatchers should therefore treat the southern extent of the forecast as a possibility rather than a guarantee and monitor conditions throughout Tuesday night.

How To Photograph The Northern Lights

Auroras are generally easiest to see under dark, clear skies away from city lights. At lower latitudes, the best chance may be toward the northern horizon rather than directly overhead. Even when aurora is difficult to see with the naked eye, a smartphone camera may reveal colors and structure that aren’t immediately obvious.

Use a tripod or stable surface and try Night Mode or a manual camera mode if available. Exposures of several seconds can reveal faint aurora, although shorter exposures are preferable when the display is bright or moving rapidly. If your phone or camera supports RAW images, that will give you more flexibility when editing later.

Why September Is A Good Month For Aurora

September is one of the most favorable times of year for aurora activity. Around the equinoxes — the September equinox occurs on Sept. 22 — the orientation of Earth’s magnetic field makes it more likely to interact effectively with the magnetic field carried by the solar wind. Known as the Russell–McPherron effect, this seasonal phenomenon makes it easier for solar-wind energy to enter Earth’s magnetic environment, increasing the chances of geomagnetic activity and aurora displays. As a result, auroras are statistically more common around the equinoxes.

Wishing you clear skies and wide eyes.