  An analysis is made of the records made by Spanish observers of a notable
aurora on 18 January 1770 in order to study the characteristics of this event.
The records indicate that the phenomenon was observed in both continental and
insular territories of Spain, in particular at San Crist\'obal de la Laguna,
C\'adiz, C\'ordoba, Badajoz, Valencia, Castell\'on, Madrid, Barcelona, and
Gerri de la Sal. The most equatorward observational site was San Crist\'obal de
la Laguna (28.48{\deg} N, 16.32{\deg} W) in the Canary Islands. In general, the
descriptions put its duration from sunset to midnight, but the observers from
C\'ordoba and Madrid report the aurora as being visible during the last hours
of the night, and it was even observed the following day at Castell\'on. All
the observers described the aurora as red in colour, while white and ash
colours were also reported at C\'ordoba and Gerri de la Sal. The brightness and
shape of auroral display changed over time. Calculations of the geomagnetic
latitudes of the observation locations gave San Crist\'obal de la Laguna as the
southernmost (26{\deg} N) to Gerri de la Sal the northernmost (35{\deg} N), and
indicate this aurora was observed over a wide range of abnormally low latitudes
for such a phenomenon. Solar activity around the event was high, with the
astronomer Horrebow registering 10 sunspot groups on that date (18 January
1770).
