Cedar Fever Guide
Updated January 1970
Ashe juniper (mountain cedar) pollen peaks across Central Texas from late December through January, driving the most intense seasonal allergy reaction in North America. This guide explains the science, the timing, and how to read real microscope counts instead of generic forecasts.
What is cedar fever?
Cedar fever is the common name for an allergic reaction to pollen from Juniperus ashei — known as Ashe juniper or mountain cedar. The tree is concentrated across the Texas Hill Country and surrounding areas, and during its narrow December–February pollination window it releases visible plumes of pollen that can drift hundreds of miles.
What makes mountain cedar uniquely brutal is the combination of three factors: an extremely concentrated geographic distribution, a tightly compressed pollination window, and pollen grains so allergenic that sensitized people react to counts that would be considered moderate for any other tree.
Generic pollen forecasts often miss the peak entirely. They average across regions and pollen types, while a real Hill Country count during a cold-front release event can exceed 20,000 grains per cubic meter — orders of magnitude above any other North American tree pollen.
The PollyMap difference
Not forecasts. Real microscope counts.
Most allergy apps publish predictions from weather models. PollyMap publishes what an Official PollyMap Partner counted under a microscope from a real air sample collected in your community. During cedar fever season, that difference is the difference between knowing why your eyes are burning and guessing.
Real samples
Microscope-verified
Local partner
One per territory
Weekly cadence
Published every week
When cedar fever hits
Pollination is sharply compressed. Trace amounts appear in November, rise quickly through December, peak in January, and fade by March.
Relative juniper pollen intensity through the year — Central Texas Hill Country.
Symptoms & relief
Cedar fever produces classic allergic-rhinitis symptoms but with unusual intensity. Many sufferers report the reaction feels closer to flu than to ordinary spring allergies.
Typical symptoms
- • Itchy, watery eyes
- • Sneezing in long runs
- • Nasal congestion and post-nasal drip
- • Sinus pressure and headache
- • Sore or itchy throat
The "fever" piece
- • Low-grade temperature elevation
- • Fatigue and body aches
- • Brain fog
- • Disrupted sleep
- • Mood and concentration impact
What helps
- Second-generation antihistamines (loratadine, cetirizine, fexofenadine) started before peak.
- Nasal steroid sprays — most effective when started 1–2 weeks before season.
- Saline nasal rinses to physically clear pollen.
- HEPA filtration indoors; keep windows closed on peak-release days following cold fronts.
- Allergy immunotherapy (sublingual or shots) — highly effective for mountain cedar specifically.
- See a local allergy clinic for severe cases — generic OTC may not be enough.
Where it hits hardest
The Ashe juniper belt runs through the Texas Hill Country and across the Edwards Plateau. The most affected metros are:
- • Austin & surrounding counties
- • San Antonio
- • San Marcos & New Braunfels
- • Fredericksburg
- • Kerrville & the Hill Country corridor
- • Waco & the I-35 corridor north
For real local counts and the latest weekly reports from across the state, see the Texas allergy season guide or browse the PollyMap knowledge library.
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