The probability of a tornado touchdown somewhere in the U.S. jumps to nearly 80 percent in May and nearly 90 percent in June.
The contiguous U.S. has warmed 2.1°F since the first Earth Day in 1970.
Climate change has increased pollen counts and the length of the pollen season, trends that are expected to continue through mid-century.
While this has been a snowy winter, the past 50 years have shown a trend of less overall spring snow cover in the Northern Hemisphere.
Spring is arriving earlier across the U.S. by an average of three days.
For the first time in 20 years, the U.S. is on track to set more record lows than record highs in 2013.
This season was the least active since 1982 and the sixth-quietest since 1950.
Foliage color and timing has been starting later, on average, in a warming world.