I expect the grape leaves will fall since the low temperature predicted for today may be in the 20s.

GDD base 50 accumulated since April 1 = 3556
http://agebb.missouri.edu/weather/reports/gddTable.asp

Here is a comparison of the GDD base 50 accumulation for the past several years.

Year	GGD accumulation base 50 April 1 to Oct 31
2014	3556
2013	3435
2012	4064*
2011	3853

*Early grape bud burst in March – 4370 GDD in season if March is counted

(Grape bud burst usually occurs around April 1)