Pollen is responsible for an extended period of seasonal allergies in North Carolina. The state’s varied climate and long growing season create a complex succession of airborne allergens rather than a single annual event. Mild winters and warm summers result in a significantly extended period of pollen exposure, often beginning far earlier than the traditional start of spring.
The General Calendar Flow
Pollen activity in North Carolina typically begins in late winter, around mid-to-late February, and persists through late autumn. The season is a continuous flow of different plant pollens, resulting in a multi-phase experience rather than a short, intense peak.
The initial wave of tree pollen can begin as early as February, gaining momentum rapidly through March and April. As certain species taper off, they are immediately replaced by other allergens approaching summer. The entire sequence usually does not end until the first hard frost, often occurring in late October or early November.
How Location Changes the Season
North Carolina’s diverse geography, including the Mountains, the Piedmont, and the Coastal Plain, significantly influences the timing and intensity of the pollen season. The Coastal Plain regions, benefiting from milder winter temperatures, often see the earliest start, with plants near the coast releasing pollen weeks before their inland counterparts.
Conversely, the Mountain regions experience a delayed start due to colder temperatures and higher elevations. Although the season begins later, the compressed growing season can sometimes lead to a more intense, concentrated period of pollination. The Piedmont region, which includes major cities, represents a transitional zone between the earlier coastal start and the later mountain peak.
Key Pollen Sources and Their Peaks
The long duration of the season results from different plant types peaking sequentially throughout the year.
Tree pollen is generally the first and most noticeable culprit, running from late February or early March through May. The most intense peak often occurs around late March or early April. Early season trees include maples and elms, followed by heavy producers like oak, pine, and hickory.
The focus shifts to grass pollen as the weather warms into late spring and summer, generally beginning in late April or May and continuing through September. Common allergenic grasses include Bermuda grass, ryegrass, and Kentucky bluegrass, with peak counts recorded from May through August.
Weed pollen takes over in the late summer and fall, primarily driven by ragweed. Ragweed season typically starts in August and lasts until the first killing frost, extending the period into October or November. This late-season surge means allergy symptoms can persist well after summer.
Tracking Daily Pollen Counts
Pollen counts provide practical, daily data for navigating the allergy season. They are measured by collecting airborne samples and analyzing the number of pollen grains per cubic meter of air. The resulting figure is classified into categories like “low,” “moderate,” “high,” or “very high,” helping individuals gauge their daily exposure risk.
The North Carolina Division of Air Quality (DAQ) operates a pollen sampler in Raleigh and publishes a daily report detailing counts for trees, grasses, and weeds. Local weather stations and allergy apps often use data from the National Allergy Bureau (NAB) or similar monitoring sites, such as those in Asheville and Winston-Salem, for real-time updates. Monitoring these counts allows allergy sufferers to adjust outdoor activities, as pollen levels are often highest in the early morning and midday.