Decode this secret winter message:

8-15-20 3-15-3-15-1 13-1-11-5-19 5-22-5-18-25-20-8-9-14-7 2-5-20-20-5-18

A=1 B=2 C=3 D=4 E=5 F=6 G=7 H=8 I=9 J=10 K=11 L=12 M=13 N=14 O=15 P=16 Q=17 R=18 S=19 T=20 U=21 V=22 W=23 X=24 Y=25 Z=26