Allergy Season Lengthens Across the US

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New data from Climate Central shows that allergy season has grown significantly longer across the United States over the past several decades. On average, the allergy season has expanded by 21 additional 'freeze-free' days since the 1970s, giving plants more time to grow and release pollen that triggers allergic reactions in many people.

Why it matters

The lengthening of allergy season is a direct result of climate change, with warmer temperatures and fewer freezing days allowing plants to bloom and release pollen for a longer period each year. This trend has major public health implications, as it means more people will suffer from seasonal allergies for a greater portion of the year.

The details

The Climate Central analysis looked at data from 1970 to the present day and found that the allergy season has grown by an average of 21 additional days across the country. Some regions have seen even more dramatic increases, with parts of the Southwest and Southeast experiencing a 30-day or more extension of the allergy season.

• The analysis examined data from 1970 to the present day.
• On average, the allergy season has expanded by 21 additional 'freeze-free' days since the 1970s.