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*Disclaimer: HeyAllergy® provides all clinical services furnished to patients in California, Florida, Texas, Illinois, Nevada, Pennsylvania. In New York, clinical services are furnished by Hey Allergy Medicine.
Real-time pollen data for San Francisco - updated daily.
San Francisco has one of the longest tree pollen seasons in the country, running from January through June. Juniper, cypress, and cedar (all related species in the Cupressaceae family) are the single most important tree allergens in the city, pollinating from January through May and sometimes into June. These are among the most common trees in San Francisco's urban landscape. Coast live oak is a native species with a long pollen season from March through mid-May, producing heavy concentrations that cause significant hay fever and asthma symptoms. Birch is not native to California but has been planted extensively as an ornamental, pollinating in late winter and early spring with highly allergenic pollen that cross-reacts with certain fruits and vegetables. Olive trees pollinate later in spring than most other trees and are a potent asthma trigger. Privet, related to olive, pollinates as the olive season ends. Acacia produces highly visible bright yellow blossoms in February and March but is actually only mildly allergenic. Eucalyptus, though iconic in San Francisco's parks and hillsides, produces relatively heavy pollen that stays close to the trees.
Grasses are considered the single most important group of plants causing allergic rhinitis in the Bay Area. Grass pollen grains are large and highly allergenic, producing strong reactions on allergy skin tests. The grass pollen season runs from mid-March through the end of July. Perennial ryegrass, Timothy grass, and Bermuda grass are the primary culprits. Wild and unmowed grass on San Francisco's hills, including Twin Peaks, Bernal Heights, and McLaren Park, produces significantly more pollen than maintained lawns. The surrounding Bay Area's open grasslands contribute additional pollen that drifts into the city on wind currents.
Weed pollen in San Francisco remains generally low to moderate compared to other U.S. cities. Nettle, sagebrush, dock, pigweed, and English plantain are the primary weed allergens detected in Bay Area air surveys. Notably, ragweed is essentially absent from the Bay Area. Local certified pollen counters have reported never detecting ragweed pollen in years of air sampling, a significant advantage over East Coast and Midwestern cities. Chinese elm blooms in fall (September through November) and acts as a moderate tree allergen during what would otherwise be weed season. Casuarina (Australian pine) and privet also contribute fall pollen.
San Francisco's famous fog creates a unique indoor allergen challenge. The city's average humidity, amplified by persistent marine fog layer, promotes dust mite survival and indoor mold growth year-round. Homes in foggy neighborhoods like the Sunset, Richmond, and Outer Mission districts face particularly high mold and dampness risks. Older Victorian and Edwardian housing stock, common throughout the city, often lacks modern ventilation, trapping moisture and mold spores indoors. Outdoor mold spores including Cladosporium, Alternaria, and Aspergillus circulate year-round, with concentrations spiking after the first fall rains break the dry summer.
Severity: Moderate
San Francisco's allergy season starts earlier than most expect. Cypress, juniper, and cedar trees begin pollinating in January, often catching newcomers off guard. Acacia produces visible yellow blooms by February. Spring-blooming elm adds to the early tree pollen load. Rainy days provide temporary relief but boost mold spore counts. Indoor allergens remain elevated as homes stay sealed during the coolest months.
Severity: High to Severe
This is San Francisco's worst allergy period. Oak pollen peaks from March through mid-April, with some species continuing into May. Birch, olive, and sycamore add to the tree pollen load. By mid-March, grass pollen season begins, overlapping with tree pollen to create the heaviest allergen burden of the year. April and May see the highest combined pollen counts. Fog-free sunny days in these months produce the worst pollen exposure.
Severity: Moderate
Grass pollen continues through July before declining. June fog (known locally as Karl) keeps western neighborhoods cooler and can suppress airborne pollen somewhat, while sunny eastern neighborhoods like the Mission, Potrero Hill, and Dogpatch experience higher pollen exposure. As summer progresses, the dry Mediterranean climate causes grass to go dormant, reducing pollen. However, outdoor mold from decaying vegetation in parks becomes a factor. Indoor mold in fog-exposed homes remains persistent.
Severity: Low to Moderate
Chinese elm provides a second wave of tree pollen from September through November. Casuarina and privet add to the fall pollen load. The most significant fall allergen event is the first rain after the dry summer, which triggers a massive mold spore release as dormant mold rapidly reactivates in newly wet soil, leaves, and organic matter. Weed pollen remains low to moderate, with nettle, sagebrush, and dock as the primary sources.
Severity: Low
December is San Francisco's lowest pollen month. Outdoor allergens drop to minimal levels. However, indoor allergens persist as homes are sealed against cold and rain. Dust mites thrive in the damp coastal air. Indoor mold in older buildings continues year-round. By late December, early cypress pollen may begin appearing, signaling the start of the next allergy cycle.
San Francisco's famous microclimates create dramatically different allergen exposures across neighborhoods. The foggy western half of the city (Sunset, Richmond, Outer Parkside) experiences lower pollen but higher mold and dampness, while the sunnier eastern neighborhoods (Mission, Potrero Hill, Noe Valley, Dogpatch) have higher pollen counts but less mold. If you are choosing where to live, understanding this east-west divide can help you match your housing to your specific allergy triggers. Someone allergic primarily to pollen may do better in the fog belt, while someone allergic to mold may prefer sunnier neighborhoods.
Unlike most major U.S. cities, San Francisco has essentially no ragweed pollen. Certified pollen counters have reported never detecting ragweed in years of Bay Area air sampling. If you relocated from the East Coast or Midwest and suffered from fall ragweed allergies, you may find significant relief here. However, do not assume your allergies are gone. Many transplants develop new sensitivities to Bay Area-specific allergens like cypress, olive, and birch within a few years of arriving.
The cypress, juniper, and cedar family is the most important tree allergen group in San Francisco, pollinating from January through May and sometimes into June. This is a much longer season than most people expect. If your spring allergy symptoms seem to start unusually early and last unusually long, cypress family pollen is likely the reason. Start daily antihistamines or nasal sprays by early January rather than waiting for traditional spring.
After San Francisco's dry summer (typically June through September with little to no rain), the first significant fall rain triggers a massive mold spore release. Dormant mold in soil, leaf litter, and organic matter reactivates rapidly when moisture returns. If you are mold-sensitive, the days immediately following the first fall rain can be among the worst of the year. Run a HEPA air purifier and keep windows closed during this period.
Much of San Francisco's housing stock dates to the Victorian and Edwardian eras, with older buildings often lacking modern ventilation and moisture barriers. Combined with the city's foggy, damp climate, these homes are prone to persistent indoor mold. If you live in an older building, invest in a dehumidifier, ensure bathroom exhaust fans are functioning, check for moisture around windows and in basements, and change HVAC filters regularly. Indoor mold is one of the most undertreated allergen sources in San Francisco.
San Francisco's diverse allergen mix means over-the-counter antihistamines may only partially address your symptoms. A board-certified allergist can identify your specific triggers through blood testing, distinguishing between cypress, oak, grass, olive, mold, and dust mite allergies. HeyAllergy offers telemedicine appointments with board-certified allergists licensed in California, with no waitlist and no commute through Muni, BART, or Bay Bridge traffic. For patients with confirmed allergies, HeyPak sublingual immunotherapy (allergy drops) treats the root cause by gradually building tolerance to your specific allergens.
March through May is typically San Francisco's worst allergy period, when oak and birch tree pollen peaks and overlaps with the start of grass pollen season. However, the city's tree pollen season starts as early as January with cypress and juniper, making the overall allergy window January through July for outdoor pollen, with mold year-round due to fog and coastal humidity.
The most important allergens in San Francisco are cypress, juniper, and cedar tree pollen (January through June), oak pollen (March through May), grass pollen (March through July), and mold spores year-round. Olive and birch tree pollen are also significant. Dust mites thrive in the damp coastal climate. A blood allergy test can identify your specific triggers.
No. Certified pollen counters in the Bay Area have reported never detecting ragweed pollen in years of air sampling. This is a major advantage for people relocating from the East Coast or Midwest, where ragweed is the dominant fall allergen. However, San Francisco has other fall allergens including Chinese elm, nettle, sagebrush, and mold.
Yes. HeyAllergy provides telemedicine appointments with board-certified allergists and immunologists licensed in California. Book a virtual consultation from anywhere in the state, have allergy blood tests ordered at a lab near you, and start a personalized treatment plan without visiting a clinic. No referral needed and no waitlist.
HeyPak sublingual immunotherapy uses customized liquid drops placed under your tongue daily. The drops contain precise doses of the specific allergens triggering your symptoms, whether that is cypress pollen, oak, grass, mold, or dust mites. Over time, your immune system builds tolerance, reducing allergic reactions and medication dependence. Most patients notice improvement within 3 to 6 months.
HeyAllergy accepts Medicare and most major PPO health plans, including United Healthcare, Health Net, Anthem Blue Cross, Anthem Blue Cross Blue Shield, Blue Shield, Cigna, Aetna, Humana, Oscar, and Tricare. Contact your insurance provider with Tax ID: 85-0834175 to confirm your specific telemedicine coverage.
San Francisco exposes newcomers to allergens they may never have encountered, particularly cypress, olive, and birch pollen, plus persistent fog-driven mold. Your immune system can develop new sensitivities within one to three years. Many transplants from drier or colder climates also discover new dust mite and mold allergies triggered by San Francisco's damp coastal environment.
HeyAllergy offers fast scheduling with no waitlist. Book a telemedicine appointment with a board-certified allergist and connect from home using your phone, tablet, or computer. No need to navigate San Francisco traffic, parking, or transit delays to sit in a waiting room.
San Francisco occupies a 47-square-mile peninsula with the Pacific Ocean to the west, the Bay to the east, and the Golden Gate strait to the north. This geography creates one of the most distinctive urban climates in the world: cool summers, mild winters, persistent fog, and microclimates that can vary by 10 to 15 degrees between neighborhoods just a few miles apart. For allergy sufferers, this translates into a complex allergen environment where pollen exposure, mold levels, and indoor allergen concentrations vary dramatically from one side of the city to the other. The foggy Sunset and Richmond districts experience fundamentally different allergen profiles than the sunny Mission or Potrero Hill, making San Francisco a city where your specific neighborhood matters as much as the season.
Juniper, cypress, and cedar trees, all members of the Cupressaceae family, are the most important allergenic trees in San Francisco. These species are ubiquitous throughout the city's parks, streets, and residential areas, and they pollinate from January through May and sometimes into June. This is an exceptionally long tree pollen season, and because it starts in winter, many residents mistake early allergy symptoms for colds or flu. Coast live oak adds a heavy pollen load from March through May, and the combination of cypress family and oak pollen makes spring in San Francisco challenging for anyone with tree pollen sensitivities. Birch, olive, sycamore, and acacia round out the tree allergen roster, each with their own peak periods that collectively stretch tree pollen exposure across nearly half the year.
San Francisco has one notable advantage over most major American cities: the effective absence of ragweed. Certified pollen counters conducting years of air surveys in the Bay Area have never detected ragweed pollen, making San Francisco one of the few large U.S. metros where fall ragweed is simply not a factor. However, grasses more than compensate. Bay Area allergists consider grasses the single most important allergen group in the region. Perennial ryegrass, Timothy grass, and Bermuda grass produce large, highly allergenic pollen grains from mid-March through July. The wild grasslands on Twin Peaks, Bernal Heights, McLaren Park, and surrounding open spaces produce significantly more pollen than maintained lawns, and prevailing winds carry grass pollen throughout the city.
San Francisco's famous fog, affectionately nicknamed Karl, is more than a weather phenomenon. It is a year-round mold generator. The persistent marine layer pushes moisture into western neighborhoods, maintaining humidity levels that support dust mite populations and indoor mold growth even during the nominally dry summer months. San Francisco's housing stock amplifies the problem. The city is famous for its Victorian and Edwardian homes, many built in the late 1800s and early 1900s with construction methods that predate modern ventilation and moisture barriers. These beautiful but aging buildings trap dampness, creating ideal conditions for mold species like Cladosporium, Alternaria, and Aspergillus. The first fall rain after the dry summer triggers an additional mold surge as dormant spores reactivate in newly wet organic matter throughout the city's parks and green spaces.
San Francisco attracts residents from across the country and around the world. Many newcomers arrive assuming the cool, foggy climate will be easy on their allergies, particularly those escaping ragweed-heavy cities in the East and Midwest. While the ragweed relief is real, transplants frequently develop new allergies within one to three years as their immune systems sensitize to unfamiliar Bay Area allergens. Cypress family pollen, olive tree pollen, and specific mold species endemic to the coastal California climate can trigger sensitivities in people who never had allergies before. This newcomer sensitization effect is well documented by Bay Area allergists and represents one of the most common reasons residents seek allergy testing after relocating.
San Francisco's density, limited parking, and traffic congestion make traditional clinic visits a significant time commitment. Adding BART delays, Muni schedules, and the challenge of finding parking in neighborhoods like Pacific Heights, the Marina, or Nob Hill, a simple allergy appointment can consume half a day. HeyAllergy's telemedicine model eliminates the logistics entirely. Board-certified allergists conduct virtual consultations, order blood allergy tests at a lab convenient to your neighborhood, and ship HeyPak allergy drops directly to your door. For a city where time is at a premium, treating allergies from your apartment or home office is not just convenient but practical.
If you experience nasal congestion, sneezing, itchy or watery eyes, coughing, or breathing difficulty for more than a few weeks per year, your symptoms likely have an allergic component worth investigating. San Francisco's complex allergen mix, spanning tree pollen, grass pollen, mold, and dust mites across different neighborhoods and seasons, means many residents take over-the-counter antihistamines for years without knowing exactly what they are treating. A board-certified allergist and immunologist can pinpoint your exact triggers, distinguish allergies from conditions like non-allergic rhinitis triggered by temperature changes, and create a treatment plan tailored to San Francisco's specific allergen profile. HeyAllergy's sublingual immunotherapy (HeyPak allergy drops) offers a long-term solution that treats the root cause of allergies from the comfort of your San Francisco home.
