Outside of the southwestern U. S. and Mexico, weather becomes much more variable. 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. By the third day - May 7 - forecasters should be able to zero in more accurately and chasers can begin to plan their final site. 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.
If weather systems expected for eclipse day are weak or poorly defined, forecasts will be less accurate and inclined to change as the day approaches. Chasers may have to travel over greater distances to reach areas where forecasters are more certain of events on eclipse day. Staying closer to home and using the satellite imagery shown on commercial television to plan at short notice is another alternative. A few hours driving may place you in an opening in an otherwise unpromising sky. Be careful when using such images, since many television stations process the pictures for a more attractive display and may lose some of the finer and smaller cloud details. The larger weather systems with the greatest amount of cloud are always visible. Watch the various forecasts from several different channels, or contact the U. S. National Weather Service or Environment Canada to allay any doubts.