G4 (Severe) Geomagnetic Storm of December 19, 1980

Name: G4 (Severe) Geomagnetic Storm of December 19, 1980
Start: 1980-12-19T03:00:00.000Z
End: 1980-12-19T21:00:00.000Z
Location: Earth

December 19, 1980 · 18 hours

A G4 (severe) geomagnetic storm began December 19, 1980, reached Kp 8- and lasted 18 hours, with a daily Ap as high as 79; at that Kp the aurora may be seen from about 47 degrees geomagnetic latitude.

The Kp through the storm

Began Dec 19, 03:00 UTC, peaked in the block from Dec 19, 15:00 UTC, ended Dec 19, 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: 8- (7.67)
NOAA level: G4 Severe
Duration: 18 hours
Highest daily Ap: 79
Highest 3-hour ap: 179
Rank since 1932: 257 of 4,139

How far south the aurora could have been seen

At Kp 8- NOAA’s scales put the aurora’s reach at about 47 degrees geomagnetic latitude: 38°N in the central US, 37°N in the eastern US, 41°N in the western US and 47°N in northern Europe.

NOAA says a G4 storm’s aurora has been seen as low as Alabama and northern California.

US cities within reach, the southernmost first

Richmond, VA 46.7° geomag.
Lexington, KY 47.0° geomag.
Lexington-Fayette, KY 47.0° geomag.
Louisville, KY 47.2° geomag.
Lakewood, CO 47.3° geomag.
Denver, CO 47.3° geomag.
Aurora, CO 47.3° geomag.
St. Louis, MO 47.3° geomag.
Overland Park, KS 47.4° geomag.
Meads, KY 47.5° geomag.

71 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
December 19, 1980	79	8-

Flares before it

Peak (UTC)	Class	Region	Before the storm began
Dec 15, 19:27 UTC	M5.6	NOAA 2840	80 hours
Dec 16, 11:54 UTC	M5.1	NOAA 2841	63 hours
Dec 16, 14:54 UTC	M4.7	NOAA 2840	60 hours
Dec 16, 10:12 UTC	M4.2	NOAA 2840	65 hours
Dec 17, 12:09 UTC	M4.0	NOAA 2841	39 hours
Dec 16, 08:09 UTC	M2.0	NOAA 2840	67 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, Dec 1 Every storm of 1980 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.