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Real-time pollen data for San Antonio — updated daily. Powered by board-certified allergists.
Mountain cedar is San Antonio's most notorious allergen and the cause of "cedar fever" — a phenomenon unique to Central Texas. Ashe juniper trees in the Texas Hill Country west of San Antonio release massive clouds of pollen that are visible from a distance, resembling wildfire smoke. Cedar pollen counts in San Antonio can reach extreme levels, producing flu-like symptoms including severe congestion, fatigue, headache, sore throat, and even low-grade fever in sensitized individuals. Cedar fever is often the first allergy experience for newcomers to San Antonio.
What makes San Antonio different: The city sits at the edge of the Hill Country, directly downwind from millions of acres of Ashe juniper. When northwesterly winds blow during winter cold fronts, cedar pollen pours into the San Antonio metro area at concentrations that dwarf pollen counts for any other allergen in any other U.S. city.
As cedar fever subsides, oak pollen takes over as San Antonio's dominant spring allergen. Live oak is the primary culprit, with pollen counts that can exceed 7,000 grains per cubic meter during peak weeks in late March and early April — among the highest oak readings recorded anywhere. Ash, elm, hackberry, mulberry, pecan, and walnut trees also contribute significant pollen loads. The transition from cedar to oak is seamless, creating a continuous allergy assault from December through May for multi-sensitized individuals.
San Antonio's mild winters mean trees begin pollinating earlier than in northern cities. Ash and elm can start producing pollen by mid-February, overlapping with the tail end of cedar season.
Bermuda grass is San Antonio's dominant grass allergen, thriving in the city's warm climate and found in residential lawns, parks, sports fields, and roadsides throughout Bexar County. Johnson grass, ryegrass, and Timothy grass also contribute. San Antonio's long warm season extends grass pollen production from April through October — a significantly longer grass season than northern cities. Grass pollen peaks in May and June but can remain elevated through early fall.
Ragweed is San Antonio's primary fall allergen, peaking in September and October. Pigweed, lamb's quarters, and other weeds are also significant. Fall elm is a notable late-season tree allergen that overlaps with the weed pollen season. The STAAMP Research pollen station — an NAB-accredited counting station in San Antonio — consistently records ragweed as the dominant fall allergen, with counts typically running from August through the first frost.
Mold is San Antonio's most persistent allergen, present in measurable quantities every single day of the year. STAAMP data shows daily mold counts ranging from 130 to over 15,000 spores per cubic meter, with dramatic spikes after rain events. Alternaria, Cladosporium, and Aspergillus are the most common species. San Antonio's warm temperatures and periodic humidity create ideal conditions for mold growth on outdoor surfaces, in soil, and inside homes with poor ventilation. Dust mites and pet dander add to the year-round indoor allergen load.
This is San Antonio's most infamous allergy period. Mountain cedar (Ashe juniper) pollen from the Hill Country floods the metro area, causing "cedar fever" — severe allergy symptoms that mimic the flu. Cedar pollen counts can reach extreme levels, particularly after cold fronts bring northwesterly winds. Many San Antonio residents consider December through February the worst allergy period of the year, and for cedar-sensitive individuals, it's debilitating.
Top allergens: Mountain cedar (Ashe juniper), mold
Severity: Very high to extreme (cedar), moderate (mold)
Tip: Cedar fever is not actually the flu — but the symptoms overlap so closely that many people take sick days before realizing it's allergies. If you get "sick" every January in San Antonio, get tested for cedar allergy. Starting sublingual immunotherapy before cedar season can significantly reduce symptoms.
As cedar winds down, oak ramps up immediately. Live oak pollen counts in San Antonio have been recorded at over 7,000 grains per cubic meter — among the highest oak readings anywhere in the country. The yellow-green pollen coating on cars, driveways, and outdoor surfaces is unmistakable during peak weeks in late March and early April. Ash, elm, hackberry, mulberry, and pecan trees add to the load. Grass pollen begins overlapping by April.
Top allergens: Oak (extremely high), ash, elm, hackberry, mulberry, early grass
Severity: High to very high
Tip: Keep car windows closed and recirculate cabin air during March and April. If you park outdoors, your car becomes coated in oak pollen — run the AC on recirculate for several minutes before opening windows.
Bermuda grass pollen peaks in early summer, with Johnson grass and ryegrass contributing. San Antonio's heat drives grass pollen production through the summer months. Mold counts can spike dramatically after summer thunderstorms, and the combination of heat and periodic rain creates ideal mold growth conditions. This is also when many residents crank up AC systems — dirty filters and neglected units can become indoor mold sources.
Top allergens: Bermuda grass, Johnson grass, mold spores
Severity: Moderate to high
Tip: Replace AC filters every 30–60 days during summer. Mold counts spike after every rain event in San Antonio — check the STAAMP daily count the day after storms.
Ragweed dominates the fall allergy season, peaking in September and October. Fall elm is a unique San Antonio allergen that adds a second tree pollen wave in autumn. Pigweed and other weeds contribute. Mold remains elevated, with STAAMP data recording counts over 15,000 spores per cubic meter after heavy fall rains. The first frost — when it arrives — ends ragweed season but mold persists.
Top allergens: Ragweed, fall elm, pigweed, mold spores
Severity: Moderate to high
Tip: Fall is San Antonio's "forgotten" allergy season — everyone talks about cedar and oak, but ragweed packs a punch. If you feel fine in spring but miserable in September, ragweed is likely your trigger.
Every winter, thousands of San Antonio residents "get sick" with fatigue, congestion, sore throat, and headaches — symptoms that perfectly mimic the flu. But if this happens every December through February and coincides with mountain cedar season, it's almost certainly cedar fever (allergic rhinitis from Ashe juniper pollen). Cedar fever doesn't cause a true fever above 101.5°F. If your temperature stays below that threshold and symptoms resolve when you stay indoors, get tested for cedar allergy. Knowing your trigger allows targeted treatment rather than ineffective cold remedies.
San Antonio has an NAB-accredited pollen counting station operated by STAAMP Research (Sylvanna Research Associates). Their daily counts are the most accurate local data available — showing specific readings for mountain cedar, oak, ragweed, grass, hackberry, mulberry, pecan, ash, fall elm, pigweed, and mold. Use this data to plan your day: when oak exceeds 1,000 grains or cedar is "Heavy," limit outdoor time and premedicate. KSAT and News4SA also publish daily pollen reports sourced from this station.
San Antonio's most brutal allergy period is the seamless transition from cedar season (Dec–Feb) to oak season (Mar–May). There is virtually no gap — as cedar pollen drops in late February, oak and ash begin ramping up immediately. If you're sensitized to both, you're looking at six continuous months of severe pollen exposure from December through May. Starting HeyPak® sublingual immunotherapy during summer or early fall gives your immune system time to build tolerance before this extended season begins.
Mold is San Antonio's year-round constant — STAAMP data shows measurable mold every single day. But counts can spike from baseline levels of 200–400 spores to over 15,000 spores per cubic meter after rain events. If your symptoms suddenly worsen 24–48 hours after a rainstorm, mold is likely the trigger. Run HEPA air purifiers after rain, keep windows closed, and ensure your AC system is clean and draining properly. Homes with foundation moisture issues or poor drainage are especially vulnerable to post-rain mold surges.
Unlike cities that get a winter break, San Antonio has no allergy-free season. Cedar fills winter, oak and ash dominate spring, grass covers summer, ragweed and fall elm take fall, and mold is constant year-round. Newcomers to San Antonio — including military families stationed at Joint Base San Antonio — frequently develop new allergy symptoms within their first 1–2 years as their immune systems encounter Central Texas allergens for the first time. If you've moved to San Antonio and developed chronic congestion, a board-certified allergist can identify exactly what you're reacting to.
With year-round allergen exposure, managing San Antonio allergies with OTC antihistamines alone is a losing battle. HeyAllergy's board-certified allergists can identify your specific triggers through blood testing and create a personalized HeyPak® sublingual immunotherapy plan targeting the Central Texas allergens causing your symptoms. Most patients notice improvement within 3–6 months. Book a telemedicine consultation from anywhere in the San Antonio metro — no clinic visit needed, no waitlist.
December through February (mountain cedar/cedar fever) and March through April (oak pollen peak) are typically the most severe. However, San Antonio has year-round allergies with no true off-season — grass pollen dominates summer, ragweed takes fall, and mold is present every day of the year.
Cedar fever is a severe allergic reaction to mountain cedar (Ashe juniper) pollen, unique to Central Texas. It causes flu-like symptoms including intense congestion, fatigue, sore throat, headache, and mild fever. Despite the name, it's not caused by a virus — it's an allergic response to the massive cedar pollen loads released from the Hill Country from December through February.
Yes. San Antonio is one of the few major U.S. cities with no allergy-free month. Mountain cedar fills winter, oak dominates spring, grass covers summer, ragweed and fall elm take fall, and mold is measurably present every single day of the year. Many residents experience overlapping allergen exposures across multiple seasons.
Yes. HeyAllergy provides telemedicine appointments with board-certified allergists licensed in Texas. You can book a virtual consultation, have allergy blood tests ordered at a local lab, receive a diagnosis, and start treatment — all without visiting a clinic. No waitlist.
HeyAllergy's HeyPak® sublingual immunotherapy drops are customized based on your blood allergy test results and formulated with allergens specific to the San Antonio region — including mountain cedar, oak, Bermuda grass, ragweed, dust mites, and mold. You place drops under your tongue daily at home. Over 3–6 months, your immune system builds tolerance, reducing symptoms and medication dependence.
HeyAllergy accepts Medicare and most major PPO health plans, including United Healthcare, Anthem Blue Cross, Blue Shield, Cigna, Aetna, Humana, Oscar, and Tricare. Telemedicine benefits vary by plan — contact your insurance provider with HeyAllergy's Tax ID (85-0834175) to confirm your specific coverage.
Very common. Newcomers to San Antonio — including military families at Joint Base San Antonio — frequently develop new allergy symptoms within 1–2 years of arrival. Central Texas allergens like mountain cedar, live oak, and Bermuda grass are unfamiliar to most people's immune systems. A board-certified allergist can identify your new triggers and create a treatment plan before your next cedar or oak season.
HeyAllergy has no waitlist. You can book an online appointment at a time that works for you and see a board-certified allergist via secure video consultation — typically within days, not weeks. Available for residents throughout the San Antonio metro area including Bexar, Comal, Guadalupe, and Kendall counties.
San Antonio consistently ranks among the worst cities in the United States for allergy sufferers, and the data supports the reputation. The city's position at the edge of the Texas Hill Country places it directly downwind of millions of acres of Ashe juniper — the source of the infamous "cedar fever" that makes Central Texas winters uniquely miserable. But cedar is just the beginning. Oak pollen counts in San Antonio have been recorded at over 7,000 grains per cubic meter, mold is measurably present every single day of the year, and the warm climate extends grass and weed pollen seasons far beyond what northern cities experience.
The result is a year-round allergy calendar with no true off-season. Cedar fills winter (December–February), oak and other trees dominate spring (March–May), grass covers summer (May–October), ragweed and fall elm take autumn (August–November), and mold provides a constant baseline 365 days a year. For the 1.58 million residents of the San Antonio metro, managing allergies isn't a seasonal inconvenience — it's a year-round health priority.
No allergen defines a city more than mountain cedar defines San Antonio. Ashe juniper trees blanket the Hill Country to the city's north and west, and when cold fronts bring northwesterly winds from December through February, they carry massive cedar pollen clouds into the metro area. These pollen clouds are sometimes visible from a distance, resembling smoke from wildfires. The pollen counts can reach levels that make outdoor activity genuinely miserable for sensitized individuals.
Cedar fever produces symptoms that closely mimic influenza: severe nasal congestion, fatigue, headache, sore throat, body aches, and a low-grade fever (usually below 101.5°F). Many newcomers to San Antonio assume they have the flu until the pattern repeats every winter. The Cleveland Clinic recognizes cedar fever as a specific clinical entity, and it's a leading cause of physician visits in Central Texas from December through February.
If cedar fever is San Antonio's winter curse, live oak is its spring equivalent. The city's massive live oak population produces extraordinary pollen volumes. STAAMP Research — San Antonio's NAB-accredited pollen counting station — has recorded oak counts exceeding 7,000 grains per cubic meter during peak weeks in late March and early April. The yellow-green pollen coating is visible on every outdoor surface, and the catkins (male flower clusters) litter the ground for weeks.
What makes San Antonio's oak season particularly challenging is its seamless connection to cedar season. As cedar pollen drops in late February, ash and elm begin pollinating immediately, followed by oak's rapid escalation in March. For individuals sensitized to both cedar and oak, December through May represents six continuous months of severe pollen exposure with no relief window.
San Antonio is home to Joint Base San Antonio — the largest joint military installation in the Department of Defense, encompassing Fort Sam Houston, Lackland AFB, and Randolph AFB. Thousands of military families rotate through San Antonio on multi-year assignments, and a significant number develop new allergy symptoms within their first 1–2 years. Their immune systems encounter Central Texas allergens — mountain cedar, live oak, Bermuda grass, local mold species — that they've never been exposed to before.
This pattern is consistent with immunological research showing that sustained exposure to novel allergens can trigger new sensitizations. Military families are particularly affected because relocations don't allow time for natural desensitization. For these families, identifying specific triggers through allergy testing early in their San Antonio assignment can prevent years of unnecessary suffering.
While pollen gets seasonal attention, mold may be San Antonio's most insidious allergen. STAAMP data documents measurable mold counts every single day — baseline levels typically range from 130 to 400 spores per cubic meter, but post-rain events can spike counts to over 15,000 spores. In October 2023, STAAMP recorded a mold count of nearly 16,000 spores following heavy rains — categorized as "Very Heavy."
San Antonio's climate creates a mold paradox: the warm temperatures that make the city livable year-round also make mold a persistent presence. Alternaria, Cladosporium, and Aspergillus species thrive on outdoor surfaces, in soil, and inside homes with foundation moisture issues or poor drainage. For allergy sufferers, this means that even when pollen is low, mold maintains a baseline level of allergen exposure that can keep symptoms active.
San Antonio's rapid growth has strained its healthcare infrastructure. The metro area spans over 500 square miles, and commuting across Bexar County for specialist appointments can consume hours. Traditional allergy clinics often have extended wait times, and allergy shot schedules requiring weekly visits are difficult to maintain across the spread-out metro.
HeyAllergy eliminates these barriers. Residents throughout San Antonio, New Braunfels, Boerne, Seguin, and surrounding communities can see a board-certified allergist from home via secure video consultation. Comprehensive blood allergy tests can be ordered to a convenient local lab, and a personalized treatment plan — including prescriptions and HeyPak® sublingual immunotherapy drops — can begin without a single in-person visit.
HeyPak® is particularly well-suited for San Antonio because the drops are customized for the Central Texas allergen profile — including mountain cedar, live oak, Bermuda grass, ragweed, and local mold species. They're mailed directly to your door, taken daily under the tongue, and monitored through follow-up telemedicine visits. No needles, no crosstown commute, no waitlist.
If you get "sick" every winter during cedar season and suspect it might be cedar fever, if over-the-counter antihistamines aren't controlling your symptoms through San Antonio's year-round allergy calendar, if you recently moved to San Antonio and developed new allergy symptoms, if you're a military family at JBSA dealing with new-onset allergies, if your symptoms worsen after every rain event (suggesting mold sensitivity), or if you have both allergies and asthma, it's time to see a board-certified allergist.
HeyAllergy accepts Medicare and most major PPO health plans including Tricare, making expert allergy care accessible for both civilian and military families throughout the San Antonio metro area.
