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USA National Phenology Network
January 17, 2018
The Spring Leaf Index is a synthetic measure of early season events in plants, based on recent temperature conditions. This model allows us to track the progression of spring onset across the country. In Florida, spring is right on time this year compared to a long-term average (1981-2010). In southern California and southwestern Arizona, spring arrived one-two weeks early.
Nature's Notebook observers submitted over 2.9 million records to the National Phenology Database in 2017. These records were submitted by 3,238 observers at 2,239 sites across the country.