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Guide

Northern Lights in Copper Harbor

Michigan (Great Lakes)

Aurora needs a dark sky, enough geomagnetic activity and clear weather. This page covers all three for Copper Harbor, Michigan, month by month.

Best Time to Go

March, September, October

Best months for an overhead display: March, September, October.

Overhead display
Kp 5 or higher
Faint glow, northern horizon
Kp 4 or higher

Tonight, Live

Checking tonight's aurora forecast...

Dark enough all year.

Best time of night: the aurora here is usually strongest around 1am standard time (2am while clocks are on daylight saving time), from about 11pm to 3am standard time.

The activity counts here cover geomagnetic activity and darkness only, not clouds. Clear, dark skies are needed to see aurora.

How to Read This Page

Three things have to line up to see the northern lights: darkness, enough geomagnetic activity for the latitude, and a clear sky.

Dark hours are the hours each night with the sun more than 12 degrees below the horizon, read on the 15th of the month.

Activity is the Kp index, a 0 to 9 scale of geomagnetic activity measured every 3 hours. Each place needs a certain Kp for a faint glow to the north and a higher Kp for a display overhead. The counts show how often dark nights reached that level from 1991 to 2025.

The best months are the three months when the largest share of dark nights reached the level. They often fall around the equinoxes, in March and in September and October, rather than in midwinter: geomagnetic storms are more common then, because the tilt of the Earth's magnetic field around the equinoxes makes it easier for the Sun's magnetic field, carried by the solar wind, to connect with it.

The activity counts do not include clouds, and history is not a forecast. Check the live maps on the night, before you head out.

Source for the equinox effect: Russell and McPherron (1973), Semiannual Variation of Geomagnetic Activity, Journal of Geophysical Research.

Hours of Darkness Each Month

Mostly Clear Nights and Cold by Month

Month Mostly clear nights in a typical month Average lowAverage snow depth
January about 6 nights 20°F-7°C12 in32 cm
February about 7 nights 18°F-8°C15 in39 cm
March about 9 nights 24°F-4°C11 in27 cm
April about 2 nights 33°F0°C4 in10 cm
May about 2 nights 39°F4°C1 in2 cm
June about 2 nights 45°F7°Cnonenone
July about 3 nights 53°F12°Cnonenone
August about 3 nights 60°F15°Cnonenone
September about 5 nights 56°F13°Cnonenone
October about 9 nights 45°F7°C1 in2 cm
November about 7 nights 35°F2°C5 in12 cm
December about 5 nights 26°F-4°C8 in21 cm

A mostly clear night here has at least 2 dark hours with under 50 percent cloud cover (a satellite estimate for the area), counted from 2001 to 2025.

Mostly clear nights and active nights are counted separately, so they are not always the same nights.

Cloud, low and snow figures are satellite and model estimates for the area around each place, 2001 to 2025, not readings from a local weather station. They are averages, not a forecast.

Biggest Nights on Record Here

  • November 11, 2025: Kp 9
  • May 10, 2024: Kp 9
  • August 23, 2005: Kp 9
  • October 30, 2003: Kp 9
  • October 28, 2003: Kp 9

The strongest dark nights here from 1991 to 2025, each strong enough for a display overhead at Copper Harbor. Clear, dark skies needed.

The Solar Cycle

In October 2024 NASA and NOAA announced that the Sun had reached the maximum period of Solar Cycle 25, which they said could last about a year. Source: NASA

Month by Month in Copper Harbor
Month Dark hours Nights reaching Kp 5 (overhead) Nights reaching Kp 4 (low on the horizon)
January 12.7 about 2 nights about 6 nights
February 11.4 about 2 nights about 6 nights
March 9.9 about 3 nights about 7 nights
April 7.9 about 2 nights about 7 nights
May 6.0 about 2 nights about 5 nights
June 4.8 about 1 night about 3 nights
July 5.5 about 1 night about 3 nights
August 7.3 about 2 nights about 5 nights
September 9.2 about 3 nights about 7 nights
October 10.9 about 3 nights about 8 nights
November 12.4 about 2 nights about 7 nights
December 13.0 about 1 night about 6 nights

Nights in a typical month. Clear, dark skies needed.

Also in Great Lakes

Dark hours: time with the sun more than 12 degrees below the horizon on the night of the 15th. Kp needed: from the place's corrected geomagnetic latitude (AACGM-v2) and NOAA's average position of the auroral oval; the horizon figure adds our own allowance of about 3 degrees. Nights: definitive Kp, 1991 to 2025, counting only nights with darkness.

Kp index data: Geomagnetic Observatory Niemegk, GFZ Helmholtz Centre for Geosciences, CC BY 4.0. Matzka, J., Stolle, C., Yamazaki, Y., Bronkalla, O. and Morschhauser, A., 2021. The geomagnetic Kp index and derived indices of geomagnetic activity. Space Weather, https://doi.org/10.1029/2020SW002641 CC BY 4.0

The month figures are history, not a forecast.

Cloud, temperature and snow data: NASA Langley Research Center (LaRC) POWER Project, funded through the NASA Earth Science/Applied Science Program. NASA POWER

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