Intense Pollen Season Forecast for UK and US in 2026

Millions of people across the United Kingdom and the United States are bracing for an unusually intense pollen season in 2026, as milder winters and shifting climate patterns trigger earlier and more prolonged allergy outbreaks. Tree pollen levels have already surged in mid-February in parts of the UK, while warmer conditions in regions like the Intermountain West have advanced the start of seasonal allergies by weeks, according to health experts.

The season unfolds in distinct phases, beginning with tree pollen from birch, oak, and ash, which peaks from March to May and affects about a quarter of hay fever sufferers in the UK. Grass pollen follows from May to July, impacting up to 95 percent of those affected, followed by weed pollen such as mugwort and ragweed through September. In the US, similar patterns emerge, with birch, cedar, and oak among the primary tree allergens, alongside grasses like rye and Kentucky bluegrass. Symptoms include sneezing, itchy eyes, runny noses, throat irritation, and fatigue, often worsening outdoors during high counts in the morning and evening.

Hay fever, or allergic rhinitis, stems from the immune system's overreaction to harmless pollen,...