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Guide

Northern Lights in Grand Marais

Minnesota (Great Lakes)

Aurora needs a dark sky, enough geomagnetic activity and clear weather. This page covers all three for Grand Marais, Minnesota, 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 3 or higher

Tonight, Live

Checking tonight's aurora forecast...

Dark enough all year.

Best time of night: the aurora here is usually strongest around 12am standard time (1am while clocks are on daylight saving time), from about 10pm to 2am 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 15 nights -1°F-18°C9 in24 cm
February about 15 nights 1°F-18°C10 in25 cm
March about 14 nights 15°F-10°C7 in18 cm
April about 11 nights 28°F-2°C4 in11 cm
May about 9 nights 39°F4°C1 in3 cm
June about 7 nights 49°F9°Cnonenone
July about 11 nights 56°F13°Cnonenone
August about 16 nights 55°F13°Cnonenone
September about 15 nights 48°F9°Cnonenone
October about 14 nights 35°F2°C2 in6 cm
November about 11 nights 22°F-6°C6 in15 cm
December about 12 nights 7°F-14°C7 in19 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 Grand Marais. 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 Grand Marais
Month Dark hours Nights reaching Kp 5 (overhead) Nights reaching Kp 3 (low on the horizon)
January 12.7 about 2 nights about 14 nights
February 11.4 about 2 nights about 13 nights
March 9.8 about 3 nights about 15 nights
April 7.9 about 2 nights about 14 nights
May 6.0 about 2 nights about 10 nights
June 4.8 about 1 night about 7 nights
July 5.4 about 1 night about 7 nights
August 7.2 about 2 nights about 12 nights
September 9.2 about 3 nights about 14 nights
October 10.9 about 3 nights about 15 nights
November 12.4 about 3 nights about 14 nights
December 13.1 about 1 night about 13 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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