It's been springing for 2-3 weeks now. In addition to the flowering trees, the non-flowering trees are cranking out the pollen. With a light shower last week, you could see everywhere the water puddled on the roads and shoulders: light yellow-green pollen scum. And like Korina says, the chorus of sniffling and sneezing (our Costco flier has three different antihistamines on sale through this weekend).