Following a given classification of geomagnetic activity, we obtained <i>aa</i> index values for the Maunder minimum (1645–1715). It is found that the recurrent and fluctuating activities were not appreciable and that the shock activity levels were very low. The <i>aa</i> index level was due almost entirely to the quiet days. Calculated average solar-wind velocities were 194.3 km s<sup>–1</sup> from 1657 to 1700 and 218.7 km s<sup>–1</sup> from 1700 onwards. Also, the coronal magnetic field magnitude and southward interplanetary magnetic field component <i>Bz</i> were lower. It is concluded that the nearly absent levels of geomagnetic activity during this period were due to lower coronal and <i>Bz</i> magnetic field magnitudes as well as to the continuous impinging on the Earth of a slow wind.