Northern Lights by Place

Quick answer: the lower a place’s Kp, the more often the northern lights reach it. Of the places here, Nuuk, Reykjavík, Tromsø and Yellowknife need none at all by NOAA’s rule — only a dark, clear night — while New York City needs Kp 8+, a storm that comes on about 64 days in an 11-year solar cycle. Across most of the lower 48 they are rare, and seen first low on the northern horizon: Chicago needs Kp 7 for that, about 194 days a cycle, and Denver Kp 8, about 64.

Place	Town	Kp overhead	Low on the horizon	Too light to see it	Longest night
Canada	Yellowknife, Northwest Territories, CA	any (0)	–	May to July	14.7 h
Greenland	Nuuk, Sermersooq, GL	any (0)	–	May to August	15 h
Iceland	Reykjavík, Capital Region, IS	any (0)	–	May to August	15 h
Norway	Tromsø, Troms, NO	any (0)	–	April to August	16 h
Yellowknife	Yellowknife, Northwest Territories, CA	any (0)	–	May to July	14.7 h
Sweden	Kiruna, Norrbotten, SE	0+	–	May to August	15.7 h
Alaska	Fairbanks, AK	0+	–	May to August	15 h
Finland	Rovaniemi, Lapland, FI	1+	–	May to August	15.3 h
Michigan	Marquette, MI	6−	–	none	13 h
Minnesota	Duluth, MN	6−	–	none	13 h
Wisconsin	Superior, WI	6−	–	none	13 h
Montana	Kalispell, MT	6	–	none	13 h
Washington	Bellingham, WA	6	–	none	13 h
Maine	Bangor, ME	6+	–	none	12.8 h
Idaho	Coeur d’Alene, ID	6+	–	none	13 h
New York	Watertown, NY	7−	–	none	12.7 h
Iowa	Mason City, IA	7+	Kp 7	none	12.7 h
Massachusetts	Pittsfield, MA	7+	Kp 7	none	12.7 h
Pennsylvania	Erie, PA	8−	Kp 7	none	12.7 h
Oregon	Portland, OR	8−	Kp 7	none	13 h
Connecticut	Hartford, CT	8−	Kp 7	none	12.7 h
Chicago	Chicago, IL	8	Kp 7	none	12.7 h
Ohio	Toledo, OH	8	Kp 7	none	12.7 h
Indiana	South Bend, IN	8	Kp 7	none	12.7 h
Nebraska	Norfolk, NE	8	Kp 7	none	12.7 h
New Jersey	Paterson, NJ	8	Kp 7	none	12.7 h
Utah	Logan, UT	9	Kp 8	none	12.7 h
Missouri	Saint Joseph, MO	9	Kp 8	none	12.5 h
Colorado	Fort Collins, CO	9	Kp 8	none	12.7 h
Kentucky	Covington, KY	9	Kp 8	none	12.3 h
Kansas	Kansas City, KS	more than 9	Kp 8	none	12.3 h

Each page opens the Northern Lights Tonight forecast on its town, with NOAA’s Kp for tonight’s dark hours. The Kp overhead is NOAA’s rule; “low on the horizon” is NOAA’s storm scale, where it comes at a lower Kp; “too light” is the months with under an hour of darkness (the Sun 12° below the horizon) mid-month.