We always get the common question... IS IT GOOD TO PHOTOGRAPH ON A CLOUDY DAY?.....many people think " No way." As photographers.... we say "YES!!!!!" Photographing on cloudy days is great. You can shoot at any time of day and avoid harsh shadows and discoloration from the sun. So if it's cloudy, you may not get the perfect sunset shot, but your portrait shots will be nice! :)
Take a look at the link below:
http://www.iheartfaces.com/2012/09/cloudy-day-photography-tutorial/