San Francisco Allergy Season Guide

San Francisco shares California's a Mediterranean climate with mild, wet winters and warm, dry summers along the coast, with hotter inland valleys. at 52 ft elevation.

San Francisco at 52 ft elevation sits within California's broader regional climate.

In San Francisco, tree pollen — including Oak, Olive, Cypress — typically dominates from late winter through spring. Bermuda grass is the most common warm-season pollinator, and Ragweed drives the largest fall pollen load.

San Francisco's local mold profile includes Cladosporium, Alternaria, Penicillium. Spore counts tend to peak after rainfall and during the warm, humid portion of the year.

Local weather — temperature, rainfall, wind, and humidity — drives day-to-day pollen levels. Dry, windy days following warm weather typically produce the highest counts, while heavy rain temporarily clears the air.