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Real-time pollen data for Santa Rosa — updated daily.
Santa Rosa sits in a valley surrounded by oak-studded hills and mixed woodland that produces one of Northern California's most intense tree pollen seasons. Valley oak and coast live oak are the dominant species, forming extensive canopies across Sonoma County's hillsides, parks, and residential neighborhoods — oak pollen peaks from March through May and is the single most impactful spring allergen in the region. Bay laurel (California bay), abundant in riparian corridors along Santa Rosa Creek and the Russian River watershed, produces highly allergenic pollen from January through March. Alder trees along creek banks begin pollinating as early as January, making them among the first tree allergens of the year. Cypress and juniper contribute winter pollen starting in December. Walnut trees, both native black walnut and commercial English walnut orchards scattered through Sonoma County, produce heavy pollen loads from April through May. Olive trees, planted extensively as ornamentals and in small commercial groves throughout Wine Country, release potent pollen from April through June. Birch, maple, and ash trees add to the spring mix. Redwood and pine from surrounding forests contribute lower-level but persistent conifer pollen. The Mayacamas Mountains to the east and the Sonoma Mountains to the south support dense mixed woodland whose pollen drifts into the Santa Rosa Plain on morning downslope winds.
Grass pollen is an extended and significant concern in Santa Rosa. The Santa Rosa Plain — the broad, flat valley floor where the city sits — supports extensive grasslands, both natural and cultivated, that produce sustained pollen loads from April through September. Ryegrass is the dominant allergenic grass species, widely present in pastures, roadsides, and open spaces throughout Sonoma County. Timothy grass, orchard grass, and fescue thrive in the region's Mediterranean climate. Bermuda grass, used in lawns, parks, and athletic fields, contributes throughout the warm season. The city's extensive park system (Howarth Park, Spring Lake Regional Park, Fountaingrove, Rincon Valley) and the surrounding agricultural landscape of vineyards, pastures, and open rangeland create distributed grass pollen sources. Vineyard cover crops — grasses and clovers planted between vine rows across Sonoma County's thousands of vineyard acres — add a distinctive Wine Country pollen source that persists until mowing or discing in late spring. Unlike Southern California, Santa Rosa's winter rains produce lush spring grass growth that generates heavy pollen loads as the grass dries and flowers in the warm season.
Ragweed is present but less dominant in Santa Rosa than in inland California regions. The primary fall weed allergens are sagebrush and mugwort, both native to Sonoma County's hillsides and open spaces, producing allergenic pollen from late summer through fall. Lamb's quarters, pigweed (amaranth), and dock contribute through the growing season. Russian thistle is less common than in Southern California but present in disturbed soils. Nettle (Urtica) grows prolifically in Santa Rosa's riparian areas along creeks and the Russian River, producing allergenic pollen from spring through summer. Star thistle, an invasive weed that has colonized vast areas of Sonoma County hillsides, blooms in summer and contributes to the pollen load. The city's ongoing development — particularly the extensive rebuilding after the 2017 Tubbs Fire — creates disturbed soil areas where invasive weeds thrive and produce concentrated pollen.
Mold is a defining allergen in Santa Rosa's climate. The Mediterranean weather pattern delivers 30+ inches of annual rainfall concentrated from October through April, creating prolonged wet conditions ideal for mold proliferation. The Russian River watershed, Santa Rosa Creek, and numerous smaller waterways create riparian corridors of perpetual moisture where Alternaria, Cladosporium, Aspergillus, and Penicillium thrive on decaying vegetation. Fallen oak leaves — which carpet the ground across Sonoma County each autumn — become prime mold substrates when winter rains arrive. Vineyard prunings and agricultural debris across Wine Country provide additional organic material for mold colonization. Post-fire landscapes from the Tubbs (2017) and Kincade (2019) fires, where vegetation is regenerating, create disturbed soil environments that support unique mold communities. Indoor mold risk is elevated in Santa Rosa's older housing stock, particularly in homes built before modern ventilation standards. Dust mites thrive during the cooler, humid months. Pet dander is a constant indoor trigger in a region with high pet ownership rates.
Santa Rosa's allergy season begins earlier than most Northern California cities. Alder trees along creek corridors start pollinating in January, joined by bay laurel and early cypress. Winter rainfall keeps the ground saturated, driving mold spore counts to their annual peak — decaying oak leaves, vineyard debris, and riparian vegetation sustain heavy Alternaria and Cladosporium loads. The Russian River and Santa Rosa Creek run at their highest levels, surrounding riparian zones remaining perpetually damp. Indoor mold risk peaks in older homes as moisture migrates through building envelopes. Ryegrass may begin pollinating in mild February weeks. Atmospheric river storms can temporarily wash pollen from the air but immediately boost mold by saturating soil and organic matter. Severity: Moderate to High (mold-driven with emerging tree pollen).
Santa Rosa's most intense pollen period. Oak pollen explodes across the valley as thousands of valley oaks and coast live oaks on surrounding hillsides release massive loads carried by morning downslope winds into the city. Walnut, ash, maple, birch, and alder produce overlapping pollen waves. Bay laurel continues through March. Grass pollen begins its spring surge as the lush green growth from winter rains starts flowering. Vineyard cover crops bloom before mowing. Mold remains elevated from ongoing rainfall but begins declining as the dry season approaches in late April. The combination of peak tree pollen with lingering mold creates the year's highest overall allergen burden. Wildflower bloom on surrounding hillsides adds to the pollen diversity. Severity: Very High.
Tree pollen declines but grass pollen reaches peak intensity as the Santa Rosa Plain's grasslands dry and flower in the warming weather. Ryegrass, timothy, orchard grass, and Bermuda produce sustained high counts. Olive trees add highly allergenic pollen from April through June — a significant trigger in Wine Country where olive trees are increasingly popular in landscaping and small commercial groves. The transition from wet to dry season means mold declines outdoors but dust increases as unpaved surfaces and agricultural soils dry. Vineyard activity (spraying, mowing, cultivation) stirs agricultural dust and organic particles. Severity: High (peak grass plus olive pollen).
Grass pollen gradually declines but remains moderate. Mugwort, sagebrush, and other weed pollens emerge. This period brings Santa Rosa's greatest wildfire risk — the combination of hot, dry conditions with thousands of acres of dried grass and woodland creates extreme fire weather. Diablo winds (hot, dry northeasterly winds similar to Southern California's Santa Ana winds) can develop in late summer, dramatically increasing fire danger. Wildfire smoke from fires anywhere in Northern California can blanket the Santa Rosa valley for days or weeks, as occurred devastatingly during the 2017 Tubbs Fire and 2019 Kincade Fire. Smoke events push PM2.5 to hazardous levels, severely aggravating allergic and asthmatic symptoms. Outdoor mold is at its lowest in the dry heat. Indoor allergens persist in sealed air-conditioned homes. Severity: Moderate (pollen) to Very High (during smoke events).
Weed pollen peaks with mugwort and sagebrush at their highest. Ragweed contributes through October. This is historically Sonoma County's most dangerous wildfire period — the Tubbs Fire ignited October 8, 2017, driven by Diablo winds that pushed flames from Calistoga into Santa Rosa in hours, destroying over 5,600 structures. The Kincade Fire burned 77,758 acres in October 2019. Wildfire smoke can persist for weeks, creating sustained respiratory crisis. As the first autumn rains arrive (typically late October or November), mold spores surge as moisture reactivates dormant colonies on the vast quantities of dried organic matter accumulated over summer. This mold spike, combined with weed pollen and potential wildfire smoke, makes October one of Santa Rosa's most challenging months. Severity: High to Very High.
Weed pollen drops sharply with the arrival of sustained rainfall. However, the wet season triggers rapid mold proliferation as rain saturates fallen oak leaves, vineyard prunings, and forest floor debris across Sonoma County. Mold counts climb through November and December. Cypress and juniper begin their winter pollination cycle in December. Indoor allergens — dust mites boosted by indoor humidity, mold in older homes, pet dander — become the primary triggers as residents spend more time sealed indoors during the rainy season. The first atmospheric river storms can cause flooding along the Russian River and Santa Rosa Creek, creating waterlogged conditions that sustain extreme mold growth. Severity: Moderate to High (mold-driven).
Santa Rosa has experienced catastrophic wildfires that fundamentally altered the city — the 2017 Tubbs Fire destroyed over 5,600 structures and killed 22 people in Sonoma County, and the 2019 Kincade Fire burned nearly 78,000 acres. Wildfire smoke blankets the Santa Rosa valley during fire events, sending PM2.5 to hazardous levels that devastate anyone with allergies or asthma. Diablo winds — hot, dry northeasterly winds that develop from late summer through fall — are the primary driver of Sonoma County's worst fires. Every Santa Rosa household should have wildfire smoke preparedness supplies: N95 or KN95 masks, at least one HEPA air purifier (ideally one per bedroom), replacement MERV 13 HVAC filters, and a portable air quality monitor. Check fire.airnow.gov daily from July through November. During smoke events, seal your home, run HEPA purifiers, and limit all outdoor exposure regardless of other allergen levels.
Oak pollen from the thousands of valley oaks and coast live oaks blanketing Sonoma County's hillsides and valleys produces Santa Rosa's most intense biological allergen period from March through May. The pollen is fine, wind-dispersed, and can travel miles from its source — morning downslope winds carry hillside oak pollen directly into the Santa Rosa Plain. During peak oak weeks, you may see a visible yellow-green film on cars and outdoor surfaces. Shower and change clothes immediately after time outdoors, especially after hiking in Annadel State Park, Taylor Mountain, or the Laguna de Santa Rosa. Keep car windows closed and run recirculating air during your commute. Time outdoor exercise for late afternoon when pollen has settled.
Santa Rosa's Mediterranean climate creates a distinctive mold pattern that catches many residents off guard. Mold peaks during the rainy season (October through April) when 30+ inches of rain saturate the valley's abundant organic matter — fallen oak leaves, vineyard prunings, creek-side vegetation, and forest floor debris. The Russian River watershed and Santa Rosa Creek corridors are persistent mold sources. Post-fire landscapes from the 2017 and 2019 fires, now regenerating with dense undergrowth, create additional mold habitats. The transition months of October and November are particularly treacherous: first rains activating mold on dry summer accumulations can produce dramatic spore spikes. If your symptoms worsen when the rainy season begins rather than improving, mold is likely a primary trigger — allergy testing can confirm this.
Living in Wine Country means exposure to agricultural allergens beyond typical urban sources. Sonoma County's thousands of vineyard acres use cover crops (grasses and clovers) planted between vine rows that bloom and produce pollen before being mowed or disced in late spring. Vineyard operations — mowing, spraying, cultivation, harvest — stir dust and organic particles into the air, particularly during the dry season from May through October. If you live near vineyards (common throughout the Santa Rosa area), peak agricultural activity days may coincide with your worst symptom days. HEPA filtration indoors and awareness of vineyard work schedules in your neighborhood can help manage exposure.
Santa Rosa's wet winters (October through April) drive residents indoors for extended periods, concentrating exposure to indoor allergens. Dust mite populations increase during the humid months. Mold can develop in older homes, particularly in bathrooms, basements, crawl spaces, and around windows where condensation forms. Many Santa Rosa homes rebuilt after the 2017 fire meet modern standards, but the city's older housing stock — Craftsman bungalows, mid-century homes, and older apartment buildings — may have inadequate ventilation for Sonoma County's wet climate. Run dehumidifiers to maintain indoor humidity below 50%, use exhaust fans during cooking and bathing, and inspect under sinks and around water heaters regularly. Allergen-proof mattress and pillow encasements address dust mites year-round.
Santa Rosa's allergen calendar has no true relief period — tree pollen begins in January, transitions to grass through summer, weeds peak in fall, mold dominates the wet season, and wildfire smoke can strike from July through November. If you're cycling through antihistamines, nasal sprays, and eye drops for months on end without lasting improvement, your immune system may need a more targeted approach. Comprehensive allergy blood testing identifies your specific Sonoma County triggers — whether oak, ryegrass, mugwort, Alternaria mold, dust mites, or other allergens — enabling personalized sublingual immunotherapy that addresses the root cause rather than just suppressing symptoms.
March through May is typically the most intense period due to peak oak and grass pollen. October can be severe when first rains trigger mold spikes while weed pollen persists and wildfire smoke remains a risk. July through October carries wildfire smoke danger that can create acute respiratory crises lasting days or weeks.
Oak pollen is the dominant spring allergen, with valley oak and coast live oak producing massive seasonal loads. Ryegrass, timothy, and Bermuda grass drive spring-through-fall symptoms. Mugwort and sagebrush are the primary fall weed allergens. Mold spores — particularly Alternaria and Cladosporium — peak during the rainy season from October through April. Wildfire smoke is a recurring acute respiratory trigger.
Three factors combine: Sonoma County's oak-dominated hillsides and grasslands produce intense pollen seasons, the Mediterranean climate's wet winters drive heavy mold growth on abundant organic matter, and the region's increasing wildfire frequency adds periodic smoke events that inflame airways and amplify allergic responses. The Santa Rosa valley's bowl-like geography can trap allergens and smoke.
Effectively yes. Alder and bay laurel pollinate in winter, oaks peak in spring, grass runs spring through fall, weeds dominate late summer and fall, and mold peaks during the entire rainy season from October through April. Indoor allergens persist year-round. Wildfire smoke can strike unpredictably from July through November.
Yes. HeyAllergy provides telemedicine appointments with board-certified allergists licensed in California. Book a virtual consultation, have allergy blood tests ordered to a convenient Sonoma County lab, and start personalized treatment — all from home. No waitlist, fast appointments available.
HeyPak allergy drops use sublingual immunotherapy (SLIT) to gradually desensitize your immune system to your specific Sonoma County triggers — whether oak, ryegrass, mugwort, Alternaria mold, dust mites, or other allergens. You place customized drops under your tongue daily at home. Most patients see improvement within 3–6 months, with 3–5 years recommended for lasting relief.
HeyAllergy accepts Medicare and most major PPO health plans, including United Healthcare, Anthem Blue Cross, Blue Shield, Cigna, Aetna, Humana, Oscar, and Tricare. Contact your insurance provider with Tax ID: 85-0834175 to confirm your specific telemedicine coverage.
Severely. Wildfire smoke contains fine particulate matter (PM2.5) that penetrates deep into lungs, inflaming airways and dramatically amplifying allergic reactions to pollen, mold, and other allergens. Sonoma County has experienced multiple catastrophic fire events — the Tubbs Fire (2017) destroyed over 5,600 structures in Santa Rosa, and the Kincade Fire (2019) burned nearly 78,000 acres. During smoke events, even people without pre-existing allergies may develop respiratory symptoms.
Santa Rosa, the largest city in Sonoma County with approximately 180,000 residents, occupies a unique position in California's allergy landscape. Sitting on the Santa Rosa Plain — a broad valley surrounded by oak-covered hills, mixed woodland, and the famous vineyards of Wine Country — the city combines Northern California's intense tree pollen seasons with a wet Mediterranean climate that drives heavy mold growth and a wildfire risk that has already proven catastrophic. The 2017 Tubbs Fire, which destroyed over 5,600 structures and killed 22 people in Sonoma County, and the 2019 Kincade Fire, which burned nearly 78,000 acres, demonstrated that wildfire is not an abstract risk for Santa Rosa residents — it is a recurring reality that profoundly affects respiratory health alongside the region's biological allergens.
Santa Rosa was founded in 1833 and incorporated in 1868, growing as the commercial center of Sonoma County's agricultural economy. The city is perhaps best known as the home of horticulturalist Luther Burbank, whose experimental gardens remain a popular attraction. Today, Santa Rosa serves as the county seat and economic hub of Wine Country, with a diverse economy anchored by healthcare (Sutter Santa Rosa Regional Hospital, Kaiser Permanente), education (Santa Rosa Junior College, Sonoma State University nearby), tourism, and the wine industry. The city's character blends urban amenities with immediate access to rural Sonoma County — vineyards, redwood forests, the Russian River, and the Pacific coast are all within a short drive.
Santa Rosa sits on a broad alluvial plain at the heart of Sonoma County, framed by the Sonoma Mountains to the south, the Mayacamas Mountains to the east (separating Sonoma from Napa Valley), and rolling hills to the north and west. This valley geography creates conditions where pollen and particulates can accumulate, particularly during calm morning hours before afternoon breezes develop. Morning temperature inversions — common during both summer and winter — trap allergens close to the ground, concentrating exposure in the hours when many residents are commuting, exercising, or spending time outdoors.
The surrounding hills are dominated by oak woodland — vast stretches of valley oak, coast live oak, and black oak interspersed with bay laurel, madrone, and mixed chaparral. This oak ecosystem is magnificent ecologically but produces one of Northern California's heaviest tree pollen loads. Morning downslope winds carry hillside pollen directly into the valley floor where Santa Rosa's residential neighborhoods, schools, and commercial areas are concentrated. The city's own urban tree canopy includes significant oak, walnut, birch, and ash plantings that add local pollen sources to the regional hillside contribution.
Oak pollen is the defining spring allergen in Santa Rosa. Sonoma County supports extensive valley oak savanna and coast live oak woodland across its hillsides, creek valleys, and parklands. Valley oaks — California's largest native oak species, reaching heights of 100 feet with spreading canopies — are particularly prolific pollen producers. Their fine, wind-dispersed pollen grains remain airborne for hours and travel miles from the source tree. When thousands of these oaks pollinate simultaneously from March through May, the cumulative pollen load across the Santa Rosa valley is immense.
The intensity of oak season is visible — during peak weeks in March and April, a yellow-green film of pollen accumulates on cars, outdoor furniture, windowsills, and any exposed surface. Residents who hike in Annadel State Park, walk the trails at Spring Lake Regional Park, or cycle along the Joe Rodota Trail during peak oak season are exposing themselves to concentrated pollen from the oak woodlands that border these popular recreation areas. Even residents who stay in urban neighborhoods are affected, as the valley's geography channels hillside pollen into the city with morning downslope air movements.
The Russian River, which flows through western Sonoma County before reaching the Pacific Ocean at Jenner, and its tributaries — including Santa Rosa Creek, which runs directly through the city — create an extensive riparian network that sustains year-round mold growth. These waterways are bordered by dense vegetation: alder, willow, bay laurel, blackberry thickets, and understory plants that provide organic material and moisture for mold colonization. During the rainy season (October through April), when Santa Rosa receives 30 or more inches of precipitation, these riparian corridors become mold factories — saturated decaying vegetation supports heavy Alternaria, Cladosporium, Aspergillus, and Penicillium populations whose spores become airborne and drift across adjacent neighborhoods.
The Laguna de Santa Rosa, a 22-mile-long wetland complex on the western edge of the city, is the largest freshwater wetland system in Sonoma County. This ecologically significant area supports abundant wildlife but also generates substantial mold and organic particulates, particularly during the transition from dry to wet season when first rains activate dormant mold colonies on the vast quantities of dried vegetation accumulated over summer. Neighborhoods adjacent to the Laguna — parts of Sebastopol Road, West Third Street, and the Bellevue corridor — experience the most direct exposure to wetland-generated mold.
No discussion of allergies in Santa Rosa is complete without addressing wildfire, which has transformed from a background risk into a defining feature of life in Sonoma County. The 2017 Tubbs Fire remains seared into the community's collective memory — driven by Diablo winds (hot, dry northeasterly winds analogous to Southern California's Santa Ana winds), the fire traveled from Calistoga in Napa County to Santa Rosa in just hours, incinerating the Coffey Park and Fountaingrove neighborhoods. Over 5,600 structures were destroyed, 22 people died in Sonoma County, and the economic loss exceeded $1.2 billion. Two years later, the Kincade Fire burned nearly 78,000 acres in northern Sonoma County, threatening Santa Rosa and forcing widespread evacuations.
For allergy and asthma sufferers, wildfire smoke is an acute respiratory crisis layered on top of chronic allergen exposure. Wildfire smoke contains fine particulate matter (PM2.5) and ultrafine particles that penetrate deep into lung tissue, triggering inflammatory responses that amplify allergic reactions to all other allergens. During smoke events — which can persist for days or weeks — PM2.5 levels in the Santa Rosa valley can reach hazardous categories, making outdoor activity dangerous for anyone with respiratory sensitivity. The smoke doesn't just affect people during the fire itself; post-fire landscapes release particulates during wind events for months afterward, and the ash and debris from burned structures (including synthetic materials, electronics, and household chemicals) can contaminate air and soil in affected neighborhoods.
Diablo wind events, which drive Sonoma County's worst fires, typically occur from late summer through early winter. These hot, dry winds descend from the northeast, replacing the region's usual cool marine influence with desert-like conditions — humidity can drop below 10%, temperatures spike, and wind gusts can exceed hurricane force. For allergy sufferers, Diablo events create multiple simultaneous hazards: extreme dryness that strips moisture from nasal passages, dust stirred from dried soils and surfaces, redistribution of settled pollen and mold spores, and the imminent threat of catastrophic wildfire. The psychological stress of fire anxiety — particularly acute in Santa Rosa since 2017 — compounds the physiological burden on respiratory health.
Santa Rosa's position at the heart of Sonoma County's wine industry adds agricultural allergen sources that most urban residents don't encounter. The county's thousands of vineyard acres use cover crops — typically grasses and clovers — planted between vine rows for erosion control and soil health. These cover crops bloom and produce pollen before being mowed or cultivated in late spring, adding a wave of grass and clover pollen that coincides with the broader grass pollen season. Vineyard operations throughout the growing season — mowing, spraying, canopy management, and harvest — stir agricultural dust and organic particles into the air.
Beyond vineyards, Sonoma County supports diverse agriculture including dairy farming, cattle ranching, apple orchards, and mixed produce. Pastureland grasses produce pollen loads, agricultural machinery generates dust, and livestock operations contribute their own allergen profile. The rural-urban interface in Santa Rosa is immediate — many residential neighborhoods border vineyards, orchards, or rangeland, placing residents in direct contact with agricultural allergen sources that would be miles away in a more traditionally urban setting.
Santa Rosa's combination of intense oak pollen seasons, sustained mold exposure during wet winters, vineyard and agricultural allergens, and recurring wildfire smoke events creates an allergen environment that demands more than seasonal antihistamine use. Many residents manage well during one season only to be overwhelmed by another — oak pollen in spring, smoke in fall, mold in winter — creating a year-round cycle of symptoms that erodes quality of life.
HeyAllergy offers Santa Rosa and Sonoma County residents convenient telemedicine access to board-certified allergists and immunologists who understand the unique challenges of living in Wine Country. Through a secure video consultation, your allergist can evaluate your complete symptom history across all seasons, order comprehensive blood allergy testing at a convenient local Sonoma County lab, and develop a personalized treatment plan that addresses your specific triggers. For patients who qualify, HeyPak sublingual immunotherapy drops can be customized to your test results and the allergens endemic to the region — oak, ryegrass, mugwort, Alternaria mold, dust mites, or any combination — delivered directly to your Santa Rosa home and taken daily under the tongue. Most patients notice improvement within 3–6 months, with 3–5 years of treatment recommended for lasting relief. Starting at $47/month, HeyPak offers a path to immune resilience in a region where beauty and allergens are equally abundant — no needles, no clinic visits, no waitlist.
