Cloudiness changes with each passing high and low.
Fortunately North America is blessed with a profusion of weather forecasting services. Forecasts suitable for initial planning should be available 5 to 6 days before the eclipse. Look for a dry westerly flow behind a strong cold front, if possible. In May 1984 those conditions brought clear skies across the southern states and a fine annular eclipse was enjoyed by millions from Georgia to the Carolinas. The motion of these systems can be forecast quite accurately about 36 to 48 hours ahead of time, allowing lots of time for planning and travel.