Texas presents a unique challenge for allergy sufferers because its immense size and diverse climate prevent a single, predictable allergy season. Mild Texas winters allow certain plants to pollinate actively, resulting in a nearly year-round cycle of exposures. Allergens shift from potent tree pollens to grasses and weeds with little respite in between. The state’s varied geography, from coastal humidity to arid deserts, further complicates the situation by supporting different dominant allergens in each region.
The Texas Allergy Calendar: A Seasonal Breakdown
The late fall and winter months mark the beginning of the most distinctive Texas allergy period, often referred to as “Cedar Fever.” This season typically begins in December and continues through February, and sometimes into early March. It dominates the allergy landscape during a time when many other parts of the country see a lull in pollen activity.
Following the winter tree pollen, the spring season brings a new wave of allergens beginning in February and extending through May. This period is marked by the release of pollen from various native trees, including oak, elm, and ash. The overlap between the end of the winter cedar season and the start of spring tree pollination can make this transition difficult for sensitive individuals.
As the weather warms, grass pollen takes over, usually beginning in April and peaking throughout the late spring and summer months, often lasting until September. Grasses such as Bermuda, Johnson, and Ryegrass thrive in the Texas heat, continually releasing pollen throughout this extended period. This cycle continues before the next wave of allergens begins.
The final major pollen cycle is driven by weeds in the late summer and fall, generally spanning from August through November. Ragweed is the primary culprit during this time, reaching its peak concentrations in September and October. This weed pollen continues to be a significant issue until the first hard frost arrives, which effectively ends the fall allergy season.
Defining the Major Allergen Sources
The winter phenomenon known as “Cedar Fever” is caused by the male Mountain Cedar, or Ashe Juniper (Juniperus ashei). A single male tree can release billions of pollen grains, which are small enough to be carried hundreds of miles by the strong winter winds. This allows the pollen to saturate the air, leading to intense and widespread allergic reactions that often mimic cold or flu symptoms.
The grasses responsible for spring and summer allergy season are primarily common species, including Bermuda, Johnson, and perennial Ryegrass. Bermuda grass, widely used in Texas lawns and fields, produces allergenic pollen that contributes significantly to the high counts experienced in late spring and summer. Johnson grass, frequently found along roadsides, unleashes its allergenic payload during the peak months of May and June.
In the fall, the most dominant weed allergen is Ragweed (Ambrosia artemisiifolia). Each plant is capable of producing up to one billion pollen grains that are light and easily airborne, allowing them to travel vast distances from their source. Ragweed thrives in the hot, mild autumns, continuing to shed pollen until the prolonged freezing temperatures of winter finally halt its growth.
Beyond pollen, environmental molds are a year-round allergen in Texas, flourishing due to the state’s high humidity. Mold spores reproduce rapidly in damp conditions, making them particularly problematic after heavy rainfall or flooding events. They are commonly found in decaying organic matter outdoors, but indoor mold growth is also a constant concern, especially in areas with poor ventilation or high moisture levels.
How Geography Affects Allergy Season
Central Texas, especially the Hill Country, experiences the most intense winter allergy season. This is because the region contains the largest concentration of Juniperus ashei trees. This dense growth makes the Hill Country the epicenter of the “Cedar Fever” phenomenon, which is a less severe issue in other parts of the state.
The Texas Coastal Plains, including cities like Houston, struggle with both grass and mold allergies due to the Gulf of Mexico’s influence. The consistently high humidity and moisture levels in this region create an ideal environment for mold spores to multiply rapidly. The warm, moist air also extends the growing season for allergenic grasses, intensifying symptoms for longer periods.
In contrast, the drier climate of West Texas, which includes the Trans-Pecos and Panhandle regions, has a different allergy profile. Tree and grass pollen are less dominant here. Strong winds frequently kick up large amounts of dust and unique regional weed pollens. Allergens like Sagebrush are more prevalent in these arid areas, meaning allergy sufferers contend more often with airborne particulates stirred up by desert conditions.