The pollen count in Greenville peaks in March–September, though allergy sufferers can experience symptoms from as early as late winter. The Southeast has one of the longest allergy seasons in the country, often running February through October due to its warm, humid climate.
The primary driver is Oak — oak trees release enormous amounts of fine pollen — a leading cause of spring allergies across the US. On warm, dry, and windy days the pollen count in Greenville can spike dramatically, while rain temporarily brings it down.
Tree pollen starts in late winter and runs through spring. Grass pollen peaks during spring. Ragweed dominates from August through October.