I shoot year round in Wisconsin as long as it is above -20 and the winds are less than 20mph as long as I can see the target. Group size no difference, number of groups are less because I'm not out there as long. Only a guess but I will bet you concentrated harder because of the snow and reaped the reward with a tighter group.
Good intentions will always be pleaded for any assumption of power. The Constitution was made to guard the people against the dangers of good intentions. There are men in all ages who mean to govern will, but they mean to govern. They promise to be good masters, but they mean to be masters.