The pollen count in Oklahoma City peaks in March–October, though allergy sufferers can experience symptoms from as early as late winter. Warm winters in the South mean pollen season can begin as early as January and stretch nearly year-round.
The primary driver is Cedar/Juniper — mountain cedar releases massive pollen loads in winter and early spring — notorious in Texas and the South. On warm, dry, and windy days the pollen count in Oklahoma City 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.