Where spring leaves are already out — and what it means for the season “Spring leaf out” is occurring earlier than average in northern states due to a warm March.

Spring allergies: Why rain actually makes them worse. ... As those raindrops hit plants, pavement, and pollen-covered surfaces, they can break open pollen grains into smaller fragments.

Why spring rain showers make Portland smell so good by: Kelley Bayern. Posted: May 7, ... plants and certain types of bacteria in the soil produce oils that accumulate on surfaces.