G1 minor geomagnetic storm and the aurora

G1 is the entry point of NOAA's geomagnetic storm scale. It matches Kp 5, and SWPC's planetary K-index page counts Kp 5 or more as a geomagnetic storm. It is the most common storm level by a wide margin.

"aurora is commonly visible at high latitudes (northern Michigan and Maine)"

SWPC's scale gives no typical geomagnetic latitude for G1, only a description: aurora is commonly visible at high latitudes, with northern Michigan and Maine named. By the oval-edge rule on SWPC's tips page, Kp 5 puts the average edge at 56 degrees geomagnetic. That covers the five Glow towns in Alaska, Canada, Iceland and Norway, and leaves the lower 48 towns just south of the edge, within viewing range to the north.

SWPC's tips page puts Kp 5 at the top of its 3 to 5 band, where the aurora moves away from the poles and becomes brighter, with more motion and formations. It also notes that under the aurora even Kp 3 or 4 can bring very nice displays, so for the five far-north towns a G1 night is a bonus rather than a requirement. With about 82 G1 storm days a year on average, it is also the level most likely to line up with a clear, dark night at a given town.

"It should be noted that the aurora can often be observed hundreds of kilometers (miles) equatorward of the actual aurora so these figures do not indicate where the aurora may be but rather the point from which it may be observed."

SWPC gives no typical latitude for G1, so only the edge rule applies. The Kp 5 edge at 56 degrees reaches 5 of them, and 10 sit within SWPC's 1000 km viewing distance of it. Duluth sits closest to that edge, 71 km south of it.

SWPC lists 1,700 G1 storms per 11-year solar cycle, falling on 900 days. Spread evenly over the cycle, that is about 155 storms and 82 storm days a year. That is 2.5 times as many storm days as G2, the next level up.