Table 6. Twenty-year trends (1998–2008) in growing season length, first autumn frost, last spring frost, and growing degree days.

Site	Growing season length(days/decade)	Last spring frost(days/decade)	First Autumn Frost(days/decade)	Growing degree days(GDD/decade)
NOAA	−1.87	6.62	4.74	114.5*
A1	0.53	−0.38	0.15	110.0**
B1	−0.56	2.43	1.88	88.4*
C1	−2.51	−0.23	−2.74	40.6
D1	1.23	−1.07	0.16	48.7

Rates of change (slopes) were derived from linear regression.

^**p<0.01,

^*p<0.05.