If you have allergies, you know allergy seasons can be rough with the constant sneezing, watery eyes and stuffy sinuses.
In the past few decades, scientists have found that seasonal allergens like mold, tree pollen and other spores have proliferated because of warmer temperatures and various environmental factors. As spring temperatures rise, so does pollen production.
Allergens are not only surviving longer than they used to - extending the pollen season by up to three weeks in some regions of North America − but they are also reproducing more frequently, which makes allergy symptoms worse for many people, according to the Association of American Medical Colleges.
Across the nation, spring approaches to differing degrees. Some areas have seen an earlier start than the long-term average between 1991 to 2020, according to the USA National Phenology Network.
In just the week of April 21, spring arrived in Bismarck, North Dakota, three days earlier than normal. It began to slow in the Northeast and northern Midwest. Portland, Maine, is three days later this year. Depending on the region where you live, spring can arrive anywhere from a week late to two weeks earlier in California, Arizona and Nevada. It's one to two weeks late on the Pacific Northwest coast.
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The number of unusually warm spring days has increased throughout the United States. On average, springtime temperatures have risen 2.4 degrees in 241 cities in the past 55 years, according to Climate Central. Compared with the 1970s, 4 out of 5 cities are experiencing at least one extra week of warmer-than-normal springtime temperatures.
In the southern half of the country, especially in the Southwest, spring has warmed the most.
Rising carbon dioxide levels in the atmosphere have continued to warm the Earth. Warmer temperatures have led to earlier springs and warmer, shorter winters, which extend growing seasons. The American Public Health Association says that as global average temperatures rise, these trends will continue and make allergies an increasing public health concern.
People with seasonal allergies may find the spring and summer months particularly challenging, especially if you live in an area prone to high pollen counts.
The Asthma and Allergy Foundation of America released its yearly report ranking the nation's top allergy capitals and explores how challenging it is to live with seasonal allergies.
The map below shows the top 36 metropolitan cities with the worst overall average of seasonal allergies this year:
It can be tricky to tell the difference between a common cold, the early signs of a COVID-19 infection or seasonal allergies because their symptoms tend to overlap.
The Centers for Disease Control and Prevention estimates that 26% of adults and 19% of children in the United States have seasonal allergies. These figures highlight the number of seasonal allergies and the importance of being aware of their symptoms.
SOURCE Centers for Disease Control and Prevention, World Health Organization, Asthma and Allergy Foundation of America, Climate Central, USA National Phenology Network and USA TODAY research