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February 23, 2017

Get your flip-flops and shorts out because spring is arriving very early this year . . . at least 2-3 weeks early across almost the entire Southeast, from San Antonio to Atlanta to Washington, D.C.  This unusually early spring is likely to keep rolling north, already bringing surprising signs of spring to portions of the central Midwest and northeastern states.

The USA-NPN is tracking the unusually early start of spring 2017 across the USA. Map from 2-22-2017
A new set of scientifically backed maps produced by the USGS-led USA National Phenology Network shows just how unusually early spring is arriving in the United States. 2017. (Public domain.)

Even Punxsutawaney Phil can’t be blamed for being baffled this year and hightailing it back to his burrow. He predicted six more weeks of winter on Feb 2, but by then spring was already springing well ahead of historical norms in much of the USA. 

While we’ve known for over a decade now that climate change is variably advancing the onset of spring across the United States, a new set of maps from the USGS-led USA National Phenology Network now demonstrates just how ahead of schedule spring is in your precise neck of the woods.

The scientifically reviewed maps and the data behind them show that you may want to keep your shorts and flip-flops handy because spring is already knocking at your door, in some places three weeks ahead of schedule. Here’s a quick national overview: spring is now making an appearance in coastal California, southern Nevada, southeastern Colorado, central Kansas, Missouri, southern Illinois, Indiana and Ohio. And it’s rolling up across West Virginia and Virginia, soon to hit Philly and Indianapolis, but it’s already sprung – days ago -- across the southern Great Plains and SE Atlantic Coast, and it was 22 days early in Washington, DC!

Why care if glorious days of spring are arriving earlier than normal?  

“While these earlier springs might not seem like a big deal – and who among us doesn’t appreciate a balmy day or a break in dreary winter weather -- it poses significant challenges for planning and managing important issues that affect our economy and our society,” said Dr. Jake Weltzin, a USGS ecologist and the executive director of the USA-NPN.

For example, changes in the timing of spring can affect human health, bringing early-season disease-carriers such as ticks and mosquitos, and an earlier, longer and more vigorous pollen season. And while a longer growing season can result in increased yields for some crops, it is risky because of the higher likelihood of plant damage caused by late frosts or summer drought. Even something as seemingly simple and beautiful as flowers blooming earlier can disrupt the critically important link between wildflowers and the arrival of birds, bees, and butterflies that feed on and pollinate the flowers. Such changes may prove beneficial to some plants and animals, including some harmful invasive ones, but may be detrimental to others.  Changes in seasons can affect economically and culturally important outdoor recreation activities, including affecting the timing of hunting and fishing seasons.

Weltzin noted that the approaches used for this study, in particular the plant leafing model though it was applied to a much longer climate dataset, were the foundation for a recent study showing that spring is arriving earlier than ever in three out of four US National Parks across the nation, and that fully half of all National Parks are experiencing extreme early onsets of spring relative to the last century.

These findings are consistent with the fact that the instrumental record shows that 2016 was the hottest year ever recorded for the globe, and that it was the third record-breaking year in a row. Researchers have noted that 16 of the 17 hottest years recorded occurred since 2000.  These new maps show that 2017, at least so far, is shaping up to be another warm one, but also that different regions exhibit variable responses over time.

Scientifically discerning the timing of spring

Lilacs (Syringa vulgaris) near old cabins in Arizona
Lilacs (Syringa vulgaris)  near old cabins in Arizona. (Credit: L Barnett)

To build the maps, the researchers with the USA-NPN used climate change indicators called the Spring Indices — models based on nationwide field observations collected about when enough heat has accumulated to initiate leafing and blooming in lilacs and honeysuckles, two common and temperature-sensitive flowering plants.

They also gathered recent nationwide heat and temperature data from the National Oceanic and Atmospheric Administration (NOAA), including daily data used for the National Weather Service, and historical daily data from a database maintained by Oregon State University, all adjusted each day to a 2-mile resolution.

When the researchers applied the plant models to the recent weather data, they were able to create national-scale daily maps of leaf emergence for these plant species.  Then, by comparing the daily maps from this year to historical maps created the same way, they created maps that showed just how different this year is relative to the long-term average (1981-2010). It is these data that reveal just how unusually early spring is arriving across most of the USA this year.

How do you know when spring has begun? Is it the appearance of the first tiny leaves on the trees, or the first crocus plants peeping through the snow? The Spring Leaf Index is a measure of these early season events in plants, based on recent temperature conditions. This model allows us to track the progression of spring onset across the country. The map shows locations that have reached the requirements for the Spring Leaf Index model (based on NOAA National Centers for Environmental Prediction Real-Time Mesoscale Analysis temperature products). (Public domain.)

What is phenology?

Phenology is nature’s calendar—when trees leaf and bloom, when birds build their nests or salmon swim upstream, or when crops mature or leaves turn color in the fall.  Phenology refers to the science focused on understanding key seasonal changes in plants and animals from year to year, and how these seasonal events vary with weather and climate.

Want to know more about observed changes in plant and animal phenology in your region over the last century? Explore the USA-NPN’s series of regional information sheets: Alaska and the ArcticGreat PlainsHawai’i and the Pacific IslandsMidwestNortheastPacific NorthwestSoutheast; and Southwest.

Become a citizen-scientist

A citizen-scientist collects field data
A Nature's Notebook citizen-scientist collects field data. (Credit: B Powell. Public domain.)

Data used to develop these maps, and to demonstrate changes in our National Parks, were collected by volunteers who recorded and shared phenological observations across the nation.  Would you like to get involved?  We need your help to collect observational data to assess how accurate our models are, and to develop similar models for other plant species – and animals too!

In three simple steps, you can become a citizen scientist and help collect critical life-cycle observations for indicator plant and animal species: 1. Join Nature’s Notebook by visiting, 2. Choose the location and species you’ll observe, and 3. Start observing and know that your observations inform scientific discovery and decision-making.

More about the USA-NPN

The USA National Phenology Network is a partnership among governmental and nongovernmental science and resource management agencies and organizations, the academic community and the public.  It is led by, and receives major funding from the US Geological Survey.


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