**Analysis by Harry Stevens:** Ken Lyons, 77, knows when strawberry plants used to bear fruit in Lebanon, N.J. In the 1980s, strawberries came within a few days of his son’s birthday on June 11. These days, Lyons’s strawberry plants peak in May. When his son, now 45, visited home for his birthday a few years ago, he was disappointed to find the strawberries already gone.
Michael Dornbrook, 71, knows when the magnolia trees used to bloom in Boston. As a student at MIT in the early 1970s, he remembers seeing their pink and white petals on his way to take his final exams in the second and third week of May. Now the magnolias often bloom in April.
As global warming nudges temperatures higher, memories of the past offer an informal account of how the seasons have changed. A formal account comes from [the USA National Phenology Network](https://www.usanpn.org/data/maps/spring?itid=lk_inline_enhanced-template) — phenology is the study of seasonal change — which reports the annual appearance of spring’s first leaves in the contiguous United States since 1981.
Spring is trending earlier across a vast U-shaped area of land stretching from coast to coast, according to my analysis of their data.
Spring’s arrival appears especially accelerated at higher elevations. In parts of California’s Sierra Nevada, for instance, trees that used to sprout leaves in mid-May now tend to do so in early April. The reason is unclear, climatologists told me, but it could be that snow has grown scarcer in the mountains, which allows the ground to absorb more of the sun’s heat, creating a feedback loop.
To know when leaves appear, it is not necessary to hire a million people across the country to vigilantly monitor trees all day. As winter fades, plants respond to the gradual accumulation of heat. So instead of watching trees, phenologists track temperature, waiting for “a set of conditions that are associated with the biological start of spring,” said Theresa Crimmins, the director of the National Phenology Network.
The data reveal broad trends in spring’s arrival time, but there is too much annual variation to forecast when leaves will appear in any given year. In a little less than half of the country, there is no clear trend at all. In some parts of the Midwest and Northwest, leaves tend to show up later than they used to.
Yet earlier springs have become more likely than later ones. In the contiguous United States, the area of land where spring leaves tend to appear earlier is four times the size of the area where leaves are trending later. And leaves’ average arrival date roughly matches the average temperature at the start of each year, according to data beginning in 1900.
> Michael Dornbrook, 71, knows when the magnolia trees used to bloom in Boston. As a student at MIT in the early 1970s, he remembers seeing their pink and white petals on his way to take his final exams in the second and third week of May. Now the magnolias often bloom in April.
I’ve been noticing this creep for years. The azaleas in my hometown that used to bloom in mid-March now bloom in February.
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**Analysis by Harry Stevens:** Ken Lyons, 77, knows when strawberry plants used to bear fruit in Lebanon, N.J. In the 1980s, strawberries came within a few days of his son’s birthday on June 11. These days, Lyons’s strawberry plants peak in May. When his son, now 45, visited home for his birthday a few years ago, he was disappointed to find the strawberries already gone.
Michael Dornbrook, 71, knows when the magnolia trees used to bloom in Boston. As a student at MIT in the early 1970s, he remembers seeing their pink and white petals on his way to take his final exams in the second and third week of May. Now the magnolias often bloom in April.
As global warming nudges temperatures higher, memories of the past offer an informal account of how the seasons have changed. A formal account comes from [the USA National Phenology Network](https://www.usanpn.org/data/maps/spring?itid=lk_inline_enhanced-template) — phenology is the study of seasonal change — which reports the annual appearance of spring’s first leaves in the contiguous United States since 1981.
Spring is trending earlier across a vast U-shaped area of land stretching from coast to coast, according to my analysis of their data.
Spring’s arrival appears especially accelerated at higher elevations. In parts of California’s Sierra Nevada, for instance, trees that used to sprout leaves in mid-May now tend to do so in early April. The reason is unclear, climatologists told me, but it could be that snow has grown scarcer in the mountains, which allows the ground to absorb more of the sun’s heat, creating a feedback loop.
To know when leaves appear, it is not necessary to hire a million people across the country to vigilantly monitor trees all day. As winter fades, plants respond to the gradual accumulation of heat. So instead of watching trees, phenologists track temperature, waiting for “a set of conditions that are associated with the biological start of spring,” said Theresa Crimmins, the director of the National Phenology Network.
The data reveal broad trends in spring’s arrival time, but there is too much annual variation to forecast when leaves will appear in any given year. In a little less than half of the country, there is no clear trend at all. In some parts of the Midwest and Northwest, leaves tend to show up later than they used to.
Yet earlier springs have become more likely than later ones. In the contiguous United States, the area of land where spring leaves tend to appear earlier is four times the size of the area where leaves are trending later. And leaves’ average arrival date roughly matches the average temperature at the start of each year, according to data beginning in 1900.
**Read more, and find out whether leaves appear earlier in your town with our interactive map:** [**https://www.washingtonpost.com/climate-environment/interactive/2024/spring-earlier-arrival-plants-map/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com**](https://www.washingtonpost.com/climate-environment/interactive/2024/spring-earlier-arrival-plants-map/?utm_campaign=wp_main&utm_medium=social&utm_source=reddit.com)
> Michael Dornbrook, 71, knows when the magnolia trees used to bloom in Boston. As a student at MIT in the early 1970s, he remembers seeing their pink and white petals on his way to take his final exams in the second and third week of May. Now the magnolias often bloom in April.
I’ve been noticing this creep for years. The azaleas in my hometown that used to bloom in mid-March now bloom in February.