A latitude network of total electron content (TEC) observations has been used to assess the contributions to day-to-day F region variability associated with variety of solar-terrestrial phenomena. Recent discussions of a proposed ''sun-weather coupling'' effect related to solar wind sector boundary (SB) crossing prompted a systematic search to document any upper atmospheric components of such a linkage. TEC data from several North American sites close to the 70¿W meridian (Narssarssuaq, Greenland (L=5): Goose Bay, Labrador (L=4); Sagamore Hill, Massachusetts (L=3): and the Kennedy Space Center, Florida (L=2) were examined during the years 1973--1975. Average daytime (0900--1700 LT) TEC values were examined for sector polarity (plus tominus versus minus to plus) effects and for overall latitudinal patterns during a period of ¿5 days from the SB crossings. Average results for the entire data set show peak excursions well within the ¿20-25% deviations associated with day-to-day variability. There is, however, a remarkable consistency in the coherence of the small amplitude latitudinal patterns. At middle to high latitudes (L=3-5), the TEC variations show an ordered transition from enhancements to depletions following an SB crossing. At lower latitudes (L=2), the opposite pattern of depletions to enchanements occurs. An identical analysis for geomagnetic activity for geomagnetic activity variations (using the planetary index Ap) reveals the well-known pattern of a transition from relatively quiet to relatively disturbed activity as a sector is crossed. A merging of these two results suggests that the manifestation in the F region of SB crossings is nothing more than small-scale version of the average ''geomagnetic/ionospheric storm effect'' that is well documented over the L=2--5 range. The latitudinal patterns for ΔTEC, and their seasonal variations, are consistent with the morphology of O/N2 varations during geomagnetic disturbances and southward IMF effects during equinoctail versus solstic periods.