Northern lights in Chicago: tonight’s chance

A city that faces the lake, east

Chicago's front yard is Lake Michigan, but the shoreline runs north to south, so the water lies east of the Loop. The northern sky from the lakefront is the North Side, Evanston and the North Shore suburbs, one continuous field of lights. On a storm night, people along the lakefront tend to see the aurora first to the northeast, above the darker water, and only when the display is strong. At Kp 6.7 the glow sits near the horizon, where the light dome over the metro is brightest. Inside the city the honest expectation is a pale reddish or greenish wash that a phone camera confirms, not a sky full of curtains.

If you cannot leave town, the end of a breakwater or a lakefront park with no streetlights in front of you is the least bad option, because it puts dark water across the northeast quarter of the sky. Give your eyes twenty minutes away from screens, and shoot a test frame toward the lake every few minutes: the sensor will show the color long before you do.

Turning the geometry around at the dunes

The south end of the lake reverses the picture. Indiana Dunes National Park stretches along fifteen miles of the Indiana coast, according to the National Park Service, and its beaches look north across open water. From there, Chicago's skyline glows off to the northwest, while due north is nothing but lake for dozens of miles. That is the closest thing to a dark northern horizon about an hour from the Loop. Inland, the other choice is distance: west past the Fox River into farm country, or north toward the Wisconsin state line, where the threshold drops slightly toward Milwaukee's Kp 6.5. Heading south does the opposite; Peoria already needs Kp 6.9.

Strong storms and the Chicago calendar

A G3 (Strong) storm is uncommon. SWPC counts about 200 strong storm periods in an average solar cycle, bunched around solar maximum, so most years bring only a few chances, and many fall in daylight or under cloud. Chicago's weather year helps in early autumn: September has the lowest NASA POWER cloud amount, 46%, and full darkness on the 15th runs from 8:35 PM to 4:57 AM. October and November keep long nights with moderate cloud, while December is the greyest month at 73%. In June the dark window shrinks to 4.4 hours, from 10:39 PM. The Illinois page compares the rest of the state, and the Milwaukee page covers the other big city on this shore.