According to the National Phenology Network (NPN), a biological research organization that works with the US Geological Survey to track the cyclical behavior of plant life across the country, this year has been marked by an unusually warm winter, which has led plants to begin spring rhythms very early. With each new leaf index map the NPN releases, the region of the country that’s experiencing a premature spring has grown including Maryland and Virginia — spring is already here. On the most recent one, released, Monday, that region includes New York.