A major shift in the weather pattern will drive a blast of cool air southeastward from Canada across the Plains, Midwest, East and South into the weekend.
The blast of air from the Canada Prairies will drive temperatures and humidity levels down all the way to Texas and eventually much of the Atlantic Seaboard.
Temperatures may struggle to top 70 around Chicago both days of the weekend.
As the cooler air blasts across the warm waters of the Great Lakes, waterspouts are likely to spin up this weekend.
In Texas, the 100-degree heat from much of this summer will be replaced by highs in the 80s with much lower humidity in such cities as Dallas, San Angelo and Houston.
In the central and northern Appalachians, in the wake of the front which marks the leading edge of cooler air, the coolest spots could have highs near 60 on Sunday.
In the Deep South, for the folks who have been enduring tropical heat and humidity this week while cleaning up after Isaac, highs in the 80s with low humidity and sunshine will settle in later this weekend into next week.
While the magnitude of cooling will be less pronounced in much of the East's I-95 corridor, humidity levels will be shaved substantially and highs will be in the 70s by early next week from Boston to New York City and Washington, D.C.
The blast of cooler air and refreshing humidity will be preceded by rounds of showers and thunderstorms, which can lead to flash flooding and localized severe weather.
The downpours and severe weather will hit portions of the Midwest Friday then the Deep South and Atlantic coast into the weekend.
In addition, folks in portions of Florida may have to deal with a weak tropical system, such as a tropical depression or tropical storm and its torrential downpours this weekend. The feature could come about of a cluster of thunderstorms over the northern Gulf of Mexico, which are part of the old remains of Isaac.
As cooler air drives into the eastern U.S. this weekend, a compensating northerly flow over the Atlantic Ocean may help drive Hurricane Leslie into Atlantic Canada early next week.
Tropical moisture from a system moving up the East Coast of the United States could help to enhance rainfall and bring gusty winds to New England and Atlantic Canada this weekend.
Typhoon Haima made a second landfall in southeastern China on Friday after leaving at least 13 dead in the northern Philippines.
Clouds will hinder skygazers across parts of the United Kingdom from viewing the final night of the Orionid meteor shower peak on Friday.
Clouds across most of Germany will spoil the final night of the Orionid meteor shower peak on Friday.
The changing of the seasons will bring beneficial rainfall to northern Brazil, a region that has experienced severe drought over the past several years.
A dramatic change to colder weather, and in some cases a taste of winter with snow, will take place into this weekend.
Raleigh-Durham, NC (2000)
No precipitation since September 26th, a record long dry spell. (The month ended with only a trace of rain.)
San Salvador Island (1492)
Columbus made landfall on San Salvador Island under clear skies -- fortunately he met no hurricanes on First Voyage through March, 1493.
Salano's Storm prevented Spanish admiral from attacking Pensacola.