Tree pollen season generally ends by late spring or early summer, typically around May to June, though this can vary depending on the region. In some areas with milder climates, tree pollen may continue to be present into June or even July. For example, in Massachusetts and the Boston area, tree pollen season usually ends around late May or early June after most spring trees finish pollinating. In North Carolina, the tree pollen season runs from February through the end of May with a peak in late March to early April. This timing can differ somewhat due to climate variations and specific local tree species.