For many years, I have conducted totally non-scientific research into the best sign of impending summer: Leaf Day.
What is that? You Ask!!
Every spring we have days of beautiful sunshine and warm temperatures. However, here in Milwaukee we don't have more than one of those kind of days in a row. The next day, like today, it is back to highs in the 40's and 50's, gray skies with a threat of rain or worse and sometimes too much wind. But on those rare warm, sunny days the buds on the trees appear which signals that the leaves are not far behind.
However, since our "spring" weather is so inconsistent (read: lousy) the trees don't know exactly when to open those buds into leaves. It does happen, but you can never predict when and you usually don't realize the leaves have actually opened until after it happens. There is no fanfare for this, no warning sounds no official news release telling us what day and time to look up.
But, I'm getting closer and I believe that TODAY is Leaf Day!!!
Yes, the sun was out yesterday... the temperatures were great and the buds opened into leaves overnight. This does not happen to all trees at the same time. You are going to look at all the trees you pass today and say "ah ha! Joanne was wrong! There is a tree with only buds. There is a tree with no leaves at all."
I don't pretend to have this theory totally nailed- down and of course different species of different trees open at different times. But take a look at the trees around you, today. Leaves! Where they there last night?
From now on you too will be watching for Leaf Day. Let me know what your research uncovers.