The November 1882 Great Aurora & Telegraph Disruptions

What happened

One of the strongest geomagnetic storms of the 19th century, with a peak Dst of roughly -386 nT and a 4-day aa index average of 214 — the highest level recorded since that index began in 1868, comparable in intensity to the 2003 Halloween storm. Widely observed aurora reached unusually low latitudes, including reports as far south as San Diego, while telegraph offices in Chicago and Milwaukee reported sparking equipment and induced currents strong enough to power a lamp with no battery connected.