Pollen Count in Irvine, CA

Irvine's Mediterranean climate—mild, wet winters and warm, dry summers—creates a nearly year-round allergy season, with mild temperatures allowing pollen-producing plants to thrive across extended windows.

Tree pollen is typically the first major wave, emerging as early as late January and peaking from February through April. Common local culprits include olive, oak (especially coast live oak), sycamore, mulberry, ash, and ornamental pine, all widely planted throughout Orange County neighborhoods and along the 405 corridor.

As tree pollen tapers, grass pollen takes over from April through July, driven by Bermuda grass, ryegrass, and fescue, which dominate Irvine's extensive lawns, parks, and greenbelts. Because tree and grass seasons often overlap in spring, many residents experience intensified symptoms in April and May.

Weed pollen follows in late summer and fall, with ragweed, sagebrush, pigweed, Russian thistle, and lamb's quarters active from August into November, particularly near open fields and foothill areas bordering the Santa Ana Mountains.

Non-pollen triggers are also significant: year-round dust mites, outdoor mold spores spiking after rain, Santa Ana wind events that dry the air and carry particulates, and regional traffic-related air pollution all contribute.

Overall, Irvine's allergy profile is defined by prolonged, overlapping pollen seasons compounded by dust and wind-driven irritants.