A recent article from the National Science Foundation describes the result of a study on when new leaves appear on plants in spring by scientists at Ohio State University and published in Nature Climate Change. The study shows that while warmer temperatures are the primary cause of earlier leaf occurrence, the number of days of rain (not the amount of precipitation) also makes a difference, and as the number of rainy days per year has been decreasing in many areas north of 30 degrees latitude, this is also affecting how early the leaves come out. The researchers calculated that a decline in rainfall frequency will lead to spring arriving an additional one to two days earlier each decade through 2100. What would cause this? The researchers think that fewer rainy days means fewer cloudy days, too, and that more sunlight reaching the plants in spring stimulates them to produce leaves earlier in the year.
