G3 (Strong) Geomagnetic Storm of October 28, 1950

October 28 to November 1, 1950 · 114 hours

A G3 (strong) geomagnetic storm began October 28, 1950, reached Kp 7+ and lasted 114 hours, with a daily Ap as high as 90; at that Kp the aurora may be seen from about 48 degrees geomagnetic latitude.

The Kp through the storm

Began Oct 28, 03:00 UTC, peaked in the block from Oct 28, 18:00 UTC, ended Nov 1, 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: 7+ (7.33)
NOAA level: G3 Strong
Duration: 114 hours
Highest daily Ap: 90
Highest 3-hour ap: 154
Rank since 1932: 287 of 4,139

How far south the aurora could have been seen

At Kp 7+ NOAA’s scales put the aurora’s reach at about 48 degrees geomagnetic latitude: 40°N in the central US, 39°N in the eastern US, 43°N in the western US and 49°N in northern Europe.

NOAA says a G3 storm’s aurora has been seen as low as Illinois and Oregon.

US cities within reach, the southernmost first

Baltimore, MD 48.5° geomag.
Indianapolis, IN 48.7° geomag.
Columbus, OH 49.0° geomag.
Lincoln, NE 49.1° geomag.
Philadelphia, PA 49.1° geomag.
Eugene, OR 49.4° geomag.
Pittsburgh, PA 49.6° geomag.
Omaha, NE 49.6° geomag.
Staten Island, NY 49.8° geomag.
Brooklyn, NY 49.8° geomag.

53 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
October 28, 1950	90	7+
October 29, 1950	62	6
October 30, 1950	51	6-
October 31, 1950	51	6-
November 1, 1950	50	6

The storm before, Oct 16 The storm after, Nov 4 Every storm of 1950 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.