Pollen is the male fertilizing agent of flowering plants, trees, grasses and weeds. Pollen is a central cause of many allergic reactions. Weather conditions affect pollen levels. The most variant factors influencing different pollen counts from approximately the same region are wind, humidity, and the proximity of the sampling equipment to pollen producing vegetation. Because pollens are small, light and dry, they can be easily spread by wind, which keeps pollen airborne and carries it over long distances. When the air is humid, such as during or after it rains, pollen becomes damp and heavy with moisture, keeping it still and on the ground.
Mountain Cedar Pollen: Cedar trees, also known as juniper trees (officially called Juniperus ashei), are evergreens that are predominant in Texas, especially in the city of San Antonio. Peak pollen production is from December through February and release of pollen occurs between 5 a.m. and 10 a.m. Pollen counts are highest on warm, sunny days. The pollen is very buoyant and may be carried by the air for miles. Among all the junipers, the mountain cedar has received the greatest attention as an allergen source largely because of the high carbohydrate content of the major protein causing a high degree of toxicity. The term cedar fever describes the dreaded allergy symptoms brought on by the pollinating cedar tree each winter. In contrary to the name, you don't actually get a fever. Instead you get itchy, watery eyes; runny nose; and sneezing.