G5 (Extreme) Geomagnetic Storm of February 7, 1986

Name: G5 (Extreme) Geomagnetic Storm of February 7, 1986
Start: 1986-02-07T09:00:00.000Z
End: 1986-02-09T21:00:00.000Z
Location: Earth

February 7 to 9, 1986 · 60 hours

A G5 (extreme) geomagnetic storm began February 7, 1986, reached Kp 9 and lasted 60 hours, with a daily Ap as high as 202; at that Kp the aurora may be seen from about 40 degrees geomagnetic latitude.

The Kp through the storm

Began Feb 7, 09:00 UTC, peaked in the block from Feb 8, 18:00 UTC, ended Feb 9, 21:00 UTC.

From 00 UT the day before to the end of the day after. Blocks in the storm are colored by level; the rest are gray.

The storm

Peak Kp: 9 (9.00)
NOAA level: G5 Extreme
Duration: 60 hours
Highest daily Ap: 202
Highest 3-hour ap: 400
Rank since 1932: 9 of 4,139

How far south the aurora could have been seen

At Kp 9 NOAA’s scales put the aurora’s reach at about 40 degrees geomagnetic latitude: 32°N in the central US, 31°N in the eastern US, 34°N in the western US and 40°N in northern Europe.

NOAA says a G5 storm’s aurora has been seen as low as Florida and southern Texas.

US cities within reach, the southernmost first

Anaheim, CA 40.0° geomag.
Corona, CA 40.1° geomag.
Los Angeles, CA 40.2° geomag.
Riverside, CA 40.2° geomag.
Moreno Valley, CA 40.2° geomag.
Chandler, AZ 40.2° geomag.
Oxnard, CA 40.2° geomag.
Hollywood, CA 40.2° geomag.
Pomona, CA 40.3° geomag.
Gilbert, AZ 40.3° geomag.

164 US cities of 150,000 people or more sit at or poleward of that line. Low on the northern horizon under a dark, clear sky; not a record of sightings.

Tonight’s aurora forecast

Day by day

The daily Ap is the mean of the day’s eight three-hour ap values.

UT day	Daily Ap	Highest Kp that day
February 7, 1986	82	8-
February 8, 1986	202	9
February 9, 1986	100	9-

Flares before it

Peak (UTC)	Class	Region	Before the storm began
Feb 4, 07:40 UTC	X3.0	NOAA 4711	73 hours
Feb 6, 06:25 UTC	X1.7	NOAA 4711	27 hours
Feb 4, 10:33 UTC	M6.4	NOAA 4713	70 hours
Feb 7, 10:29 UTC	M5.2	NOAA 4711	during it
Feb 5, 12:53 UTC	M3.0	NOAA 4711	44 hours
Feb 3, 20:40 UTC	M2.3	NOAA 4711	84 hours

The strongest M and X class flares GOES recorded from four days before the storm began to its end, the window in which a coronal mass ejection launched with a flare usually arrives. A flare in this list is context, not proof of the cause: many storms come from coronal holes, and many flares launch nothing toward Earth.

The storm before, Jan 27 The storm after, Feb 21 Every storm of 1986 The strongest on record This day in weather history Tonight’s aurora forecast

Sources

Kp and ap from GFZ Helmholtz Centre for Geosciences, Geomagnetic Observatory Niemegk, licensed 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, doi:10.1029/2020SW002641; data doi:10.5880/Kp.0001. Storms, levels and aurora reach worked out by WeatherOverTime from those values and NOAA’s space weather scales. Definitive through August 31, 2026; later values are preliminary. Rebuilt 2026-09-24. Flares from NOAA NCEI’s GOES X-ray flare reports (1975 to 2017) and SWPC’s edited solar event lists, public domain; classes as NOAA recorded them at the time.