By one measure, spring could come a few weeks early across much of the country.

2018 first day of spring
Credit: Dan Kitwood / Staff

Most people know that the first day of spring is associated with the Vernal Equinox, which falls on March 20 this year. But in 2018, the flowers might start to bloom a bit earlier than usual in some parts of the United States, continuing a trend that’s deviated from the norm in recent years.

The USA National Phenology Network, a group that works in collaboration with the federal government to study the seasonal life cycles of plants and animals, said in a new report that spring — which it defines according to plant life and temperature patterns — is arriving two to three weeks early across much of the West Coast, South, and Mid-Atlantic states in 2018.

While some may consider the warming temperatures reason to celebrate, there is a worrisome caveat: climate change. The recent long-term average of 30 years, from 1981 to 2010, had spring arriving closer to what we consider “normal” times.

“The timing of leaf-out, migration, flowering and other seasonal phenomena in many species is closely tied to local weather conditions and broad climatic patterns,” the USA National Phenology Network said in a “Status of Spring” update on its website.

So what areas will experience leaf budding and rising temperatures earlier than usual? Cities like Portland, Ore., Baltimore and Cincinnati will be treated to spring at least two weeks in advance.

Jake Weltzin, an ecologist with the U.S. Geological Survey (USGS), told Travel + Leisure that earlier projections on the USGS-NPN Index showed much of the south, from Texas to South Carolina, experiencing a slow start to spring. “But in the last week or so, probably because of high-level shifts in the atmosphere, things have flipped,” Weltzin said. The south is now on track for an early spring too.

Still, Weltzin added, things can remain a bit chilly for a while. “Gardners take note,” he said. “Though it's warm, there's still a potential for frost. And, we should watch for early ticks, mosquitos and other insect pests, and allergy sufferers should make plans as pollen season kicks into gear.”