Will Washington see northern lights? ‘Amazing’ fall phenomenon could impact odds

The leaves aren’t the only thing that could change colors as fall gets underway.

The fall equinox, along with its spring counterpart, is one of the best times of the year to see the northern lights, according to EarthSky.

That’s especially true in Washington state, which is often just outside of the range where the northern lights are visible.

What could be in store for local stargazers as the seasons change?

Here’s what to know: When is the fall equinox in 2025?

The autumn equinox officially marks the first day of fall.

In 2025, the fall equinox lands on Monday, Sept. 22, at 11:19 a.m. Pacific Daylight Time. What are northern lights?

Auroras are caused by “electrons colliding with the upper reaches of Earth’s atmosphere,” according to the National Oceanic and Atmospheric Association.

The sun’s particles collide with oxygen and nitrogen atoms, resulting in a spectacular light show that’s known as aurora borealis in the Northern Hemisphere.

“Auroras are one of our night sky’s most dramatic spectacles,” NASA said.

Typically, auroras form about 80 to 500 kilometers — about 50 to 311 miles — above the Earth’s surface, the federal weather agency said on its website. Why is aurora borealis more visible at fall equinox?

Auroras are more visible during the fall and spring equinoxes due to a natural phenomenon known as the Russell-McPherron Effect, according to Shawn Dahl, service coordinator at NOAA’s Space Weather Prediction Center.

“Around the equinoxes, the magnetic field … (is) more effectively aligned with the sun” due to the tilt of the Earth, Dahl told McClatchy via phone. “So that magnetic field from the sun can more effectively or easily connect with Earth’s magnetic field.”

The effect is strong enough to have a noticeable impact on Washington’s odds of seeing the northern lights, he said.

“I don’t understand it entirely, but it really is amazing how this does tend to work,” Dahl said.

Auroras are caused by the interaction between charged particles from the sun and the earth’s magnetic field, according to NASA.

That doesn’t mean the sun emits more charged particles around the equinoxes, when the two magnetic fields are better aligned, Dahl said.

“It has nothing to do with solar activity increasing,” Dahl said. “It has to do with how earth becomes a little bit more susceptible to an enhancement in only geomagnetic activity.”

In October 2024, the sun reached its solar maximum period, the high point in its 11-year cycle of magnetic activity, NASA and NOAA said.

Dahl said we’re still in a period of heightened solar activity.

“There are periods where we escalate again,” he said.

Solar-magnetic activity can come in the form of coronal mass ejections — large releases of particles spewed by the sun during a magnetic storm — or solar winds, which are streams of charged particles emitted by the sun.

Dahl said the Russell-McPherron Effect tends to impact solar winds more, so the coronal mass ejections that brought dazzling light displays around the solar maximum won’t necessarily be heightened around the equinox.

“There’s so much variability in how these (coronal mass ejections) impact Earth,” Dahl said. Who will see northern lights?

If you’re hoping to see the northern lights in the days around the equinox, Dahl recommends checking NOAA’s website for geomagnetic activity updates.

The agency also maintains an experimental aurora forecast.

Typically, the aurora viewing line extends to northern Washington at a planetary K-index — which measures the magnitude of geomagnetic storms— of five or six, according to NOAA.

That corresponds to a G1 or G2 on the scale used to measure the effects of geomagnetic activity. The scale ranges from G1, which signifies a minor storm, to G5, an extreme storm. A G3 storm brings the rest of Washington state into the picture, although odds of seeing the aurora are still considered relatively low at that level.

Dahl said NOAA’s forecasts take the alignment of the earth and sun’s magnetic fields into account.

“It doesn’t necessarily mean the odds are better for seeing the aurora, because we’re already taking that into account in our forecast,” Dahl said. “We strengthen it up a little bit from what we would normally say … if this were in June.” How long will aurora season last?

According to Dahl, you have a better chance of seeing an aurora within a few weeks of the fall equinox, before the “aurora season” effect starts to fade.

“We usually start to take this into account when we’re within 30 days,” Dahl said. “But it’s really a pretty narrow window, and it’s usually around that two to three week time-frame in and around the equinoxes.” What’s the best way to see the northern lights?

According to the National Oceanic and Atmospheric Administration, these are some of the few ways you can increase your odds of seeing the northern lights in the Northern Hemisphere: * Go to a place where you have a view to the north * Wait until it’s dark outside * Go to a place with as little light pollution as possible * Often, the most active auroras will come between the hours of 10 p.m. and 2 a.m.