We've been unlucky for totals across the US recently... but there will be one in 2017!
The biggest temperature drop I experienced for a non-total (but very close) is 10 degrees in May 1994. (90 to 80F).
In Libya we measured a 15 degree (F) temperature drop... but that was in the desert near noon. That eclipse was also amazing because we could see the wall of the shadow race across the desert to us... awe inspiring! And we even got a shadow bands movie!
Here is where you can see the shadow bands movie:
http://space.rice.edu/ecl...clipse_2006/carmona/
There are a lot of other images and movies on that site
http://space.rice.edu/eclipse/
I was in China last year and am going again this year! This will be my ninth totality!