Good site for calculating weather correction
 

If you ever wanted to know what you would have ran if the weather had been different then here's a good site to run the calculation. I've used it many times with good accuracy.
http://www.xs-fx.com/pain/ws.htm

http://www.modulardepot.com/density2.php - To get the DA

http://www.modulardepot.com/density.php - To get the correct ET at sealevel.

-Mark