The vertical atmospheric electric field was measured at Vostok, Antarctica (78¿S, 107¿E) during the period March--November 1974 using a rotating dipole antenna. It is found that the electric field is depressed by ~15% 1--3 days following the passage of solar magnetic sector boundaries. This effect is more clearly evident in the austral winter when Vostok is in continuous darkness. No significant difference is found between the away-to-toward boundaries. This effect is more clearly evident in the austral winter when Vostok is in continuous darkness. No significant difference is found between the away-to-toward boundaries and the toward-to-away boundaries. These results suggest the possibility that the global fair-weather atmospheric electric field is an important factor in the solar activity-weather relationships.