Climate Change Causes Hay Fever Season to Start Earlier than Ever!

Climate Change Causes Hay Fever Season to Start Earlier than Ever!

This year, spring seemed to arrive earlier than usual in many parts of the United States, which almost everybody with seasonal allergies certainly realized.

Studies have shown that the pollen that triggers symptoms of allergy in many, has been arriving earlier than in previous decades as a result of climate change, which makes winters warmer and plants start blooming earlier.

With that being said, here is how the longer plant growing season brought on by warmer winters is affecting millions of hay fever sufferers in the United States.

As per National Oceanic and Atmospheric Administration, “February continued the concerning mild start to 2023, with much of eastern U.S. seeing record or near record warm temperatures. The average temperature across the U.S. last month was no less than 36.5 degrees F, 2.7 degrees over the 20th century average, ranking in as the warmest third of the 129 year climate record.”

This last February was the warmest on record in Virginia.

Three other states had their third-warmest February ever, and 8 other states east of the Mississippi River experienced their second-warmest February in history as well.

There was one exception, though: This February saw colder temperatures than usual in 6 western states: California, Colorado, Arizona, Oregon, Idaho and Nevada.

“Meteorological winter” refers to the coldest 3 months of the year, which are considered December, January and February, even though there is still one more week of winter on the astronomical calendar, the latter of which is based on the Earth’s position in relation to the Sun.

Appalachia, and the Upper Midwest experienced their second-warmest winters ever, and Massachusetts experienced its warmest winter on record. 21 additional states experienced one of their top ten warmest winters.

Another six states experienced one of their ten wettest winters, and Wisconsin experienced its wettest winter ever. With that being said, more rain during a plant’s growing season promotes earlier and quicker growth, according to studies.

USA Today reported that “Observers are reporting early leaf outs of common lilac in Pennsylvania, brilliant yellow blossoms of forsythia in Maine as well as the American witch hazel in New York.”

An environmental activist by the name of Lois Krauss shared via Yahoo News that “I am sitting outside on March 7 and all of my daffodils are blooming, and it is ridiculous.”

The National Phenology Network, which records the emergence of spring by monitoring the flowering of popular plant species across the country that are normally among the first to sprout leaves, including honeysuckles and lilacs, reported that leaves were growing the earliest they have ever in several regions of the eastern U.S. back in early February.

Furthermore, buds bloomed 32 days earlier than usual in New York City.

The National Phenology Network also reported that “Spring leaf out goes on to spread north, arriving days to weeks earlier than the average (1991-2020) in the Southeast, lower Midwest, and mid Atlantic. Kansas City, MO is nine days early, Nantucket, MA is 35 days early.’

They went on to mention that “spring bloom has arrived in southern states as well, days to weeks earlier in the Southeast,” including by no less than 22 days in Norfolk, Va.

The National Phenology Network director, Teresa Crimmins stated that “It is a little unsettling, it is certainly something that’s out of the bounds of when we would normally expect spring. It perhaps is not surprising, given the trajectory our planet is on, but it’s surprising when you live through it.”

Meteorologist at Climate Central, Lauren Casey, told CNN that “Because of climate change, we are seeing an earlier and longer season for plants growing now, which make pollen – the enemy of many Americans who suffer from pollen allergies – and mold allergies too. Pollen can trigger an asthma attack as well, which of course is more serious for those that suffer from asthma.”

Climate change-related carbon dioxide emissions also promote earlier and quicker plant development.

Higher atmospheric carbon dioxide concentrations accelerate photosynthesis because plants absorb carbon dioxide throughout the process.

Hay fever is brought on by allergic responses to mold spores and plant pollen in the atmosphere.

The allergy season is prolonged and made worse as a result of earlier and quicker plant development brought by greater CO2 concentrations, hotter temperatures, and more precipitation.

In mid-February, The Washington Post reported “unusually high winter temperatures have led to a historically early and more intense tree pollen explosion.”


Katherine is just getting her start as a journalist. She attended a technical school while still in high school where she learned a variety of skills, from photography to nutrition. Her enthusiasm for both natural and human sciences is real so she particularly enjoys covering topics on medicine and the environment.

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