Spring Pollen Allergy Forecasts
Weather Effects on Pollen Counts Can Determine Severity of Allergies
Feb 19, 2008
How Weather Affects Allergies
Certain weather conditions can either increase or decrease the production of pollen, from both tree and grass sources. According to the American College of Allergy, Asthma and Immunology (ACAAI), there are several weather factors that affect pollen allergy severity.
- Mild winter – A mild winter can mean an early start to the allergy season, as trees tend to pollinate earlier. Pollen counts can increase with a mild winter, and intensify during a mild spring.
- Wind – Wind can spread pollen and spores more rapidly, increasing overall exposure to pollen. Dry, windy conditions yield higher pollen counts. Hot, windy weather can increase allergy symptoms because these weather conditions produce a higher distribution of pollen and spores.
- Late freeze – A late freeze can decrease or delay tree pollination, causing lower pollen counts.
- Rain – Rain can reduce tree pollen count by washing the pollen from the air, providing relief to allergy sufferers. Increased rain amounts in fall or winter can cause an increase in spring tree pollination amounts. Increased rain amounts in spring can stimulate grass growth, producing more pollen.
Some severe weather events can have an effect on pollen seasons. Although the pollen season for a location may be the same year to year, it can be affected by weather. El Nino conditions producing warmer, wetter weather can represent an early spring. Severe El Nino conditions, such as during the 1998-99 season, can produce earlier tree pollination and higher pollen counts.
Allergy Season Forecasts
Forecasts for the pollen allergy season can be difficult to determine. Analyzing winter weather conditions, specifically freeze dates, can be a useful way to determine the severity of the allergy season. However, as weather forecasts change and future weather trends are almost impossible to forecast, allergy season forecasts can be hard to accurately predict. Relying on past weather data and current pollen counts is the best way to determine an allergy forecast.
Pollen Counts by National Allergy Bureau
The American Academy of Allergy, Asthma and Immunology (AAAAI) uses pollen counts taken across the United States to determine spring allergy season severity. A pollen count is used to “measure the amount of airborne allergens present in the air” (AAAAI, 2008). Using these pollen and spore counts from air samples at the stations, the AAAAI National Allergy Bureau (NAB) can provide accurate current pollen and mold counts for allergy sufferers, for many locations. Counts are available online for five US regions and Canada.
Weather Affects Pollen Counts
In addition to impacting the allergy season, weather elements can also affect the pollen count. Several factors affecting the pollen count include
- Soil temperature
- Number of day above 55 degree F
- Duration of freezing temperatures during winter
- Moisture levels, or humidity
For more information on current pollen counts, contact the American Academy of Allergy, Asthma and Immunology.
