How Do We Know If Spring Has Sprung?

ST. PAUL, Minn. (WCCO) -- In a matter of days, we've gone from warm and muggy to flat out cold.

The Twin Cities can't seem to shake the side effects of winter. That had us wondering: How do we know if spring has sprung? Good Question.

Jeff Wagner bundled up to find out how far behind schedule we are.

Layered up like it's still winter, Minnesotans battled a brutal Monday chill that was helping to subdue any semblance of a season change.

"April is about six-degrees below normal right now," said state climatologist Pete Boulay, adding that average temperature on April 25 is around 60 degrees. It didn't even top 40 degrees.

The temperature is impacting the ability for spring to truly emerge.

"Saturday, that 70-degree air, kind of, you know, put … the pedal to the floor on phenology. Then a day like today just pull on the brake and everything slows down," he said.

Cold days mean cold soil, stunting plant growth and evolution. Phenology is like nature's calendar. It represents the life cycle of plants and habits of animals across the seasons.

"Spring started a few days, up to a week behind. And now we're increasing the span a little bit here as we keep having more and more cold days," he said.

That means the local phenology could be off schedule as well. Boulay tracks the phenology of certain plants and animals each year.

Based on his research, dandelions and Siberian Squill are both behind schedule by at least a week, if not two weeks. Lilac buds were forming with the expectation to bloom around Mother's Day, but Boulay's eyes and the upcoming chilly week have him thinking lilacs will be delayed as well. Grabbing shade underneath a tree is another spring benchmark.

The National Phenology Network tracks when leaves form on trees, known as "leaf out." Some parts of the country are ahead of schedule, while others are behind. The NPN's latest Daily Spring Index Leaf Anomaly shows that Iowa and parts of southern Minnesota are considered about eight-to-nine days late.

The good news is that if nature can't provide that spring feeling, we humans will find a way. The Minnesota Twins take the field in early April, even if snowfall creeps toward the home opener.

Restaurants start putting tables and chairs outside in preparation of patio season. Signs of a seasonal change regardless if Mother Nature is on time.