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Status of Spring
The USA-NPN is tracking the start of the spring season across the country using models called the Spring Leaf and Bloom Indices.
How does this spring compare to "normal"?
Spring has started to arrive in southern states. In Florida, spring is right on time compared to a long-term average (1981-2010). In southern California and southwestern Arizona, spring arrived one-two weeks early.
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 Spring Index maps offered by USA-NPN shed light on plant and animal phenology, based on local weather and climate conditions.
Spring Indices: Indicators of phenological activity
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 synthetic 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 at right 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).
Learn more about the Extended Spring Indices and the data products available.
USA-NPN also produces a suite of Accumulated Growing Degree Day map products.
View a week-by-week animation of the Spring Leaf Index map (Jan 1, 2017-May 15, 2017)
Re-use of Maps and Data
Content, maps and data accessible via usanpn.org are openly and universally available to all users. USA-NPN is not responsible for content or the use of the data. Content may be re-used and modified with appropriate attribution (e.g., "source: USA National Phenology Network, www.usanpn.org"). See our complete Content Policy and Data Use Policy.