Pollen Count in Glendale, CA

Glendale, CA sits in a semi-arid Mediterranean climate zone at the edge of the San Fernando and San Gabriel Valleys, producing a long, overlapping allergy season with relatively few dormant weeks.

Tree pollen dominates from late January through May, with heavy contributions from olive, California sycamore, coast live oak, mulberry, ash, walnut, and non-native pines and cypress commonly planted along local streets and foothills.

As trees taper off, grass pollen rises from April through July, driven primarily by Bermuda, ryegrass, fescue, and Kentucky bluegrass used throughout residential lawns and parks.

Weed pollen takes over in late summer and fall, peaking August through October, with Russian thistle (tumbleweed), sagebrush, pigweed, lamb's quarters, and western ragweed as key offenders—ragweed is less dominant here than in the Midwest but still clinically relevant.

Significant overlap occurs in April–June, when late tree pollen meets peak grasses, often intensifying symptoms.

Non-pollen triggers are substantial: year-round dust and dust mites, outdoor molds that spike after winter rains and in irrigated landscaping, wildfire smoke in late summer and fall, and high ozone and particulate pollution trapped by surrounding mountains.

Overall, Glendale's allergy profile is defined by a nearly year-round pollen calendar compounded by dry air, poor air quality, and episodic smoke.