Coincidence? I Wonder.

The three schools graphed here are :

Carnegie Science Center in Pittsburgh, Pennsylvania
Miami University in Oxford, Ohio
Daggett Elementary School in Fort Worth, Texas

There are some dips and drops in the temperature graph that appear to occur at the same time. Is this just a coincidence? If these temperature drops are related to a cold front passing through, can we determine how fast the front was moving by measuring times and distances between the sites?