Yes, there is pollen in the summer, and plenty of it. Grass pollen is the dominant airborne allergen from late spring through the summer months, making this season one of the most challenging for the roughly 25.7% of U.S. adults who deal with seasonal allergies. By late summer, weed pollen joins in, creating an overlap that can keep symptoms going well into fall.
Grass Pollen Drives Most Summer Allergies
Grasses are the primary pollen source during summer. While tree pollen dominates in spring, grass pollen takes over as temperatures rise and remains the leading trigger of allergy symptoms through June, July, and into August. Some of the most common allergy-causing grasses include Timothy, Kentucky blue, Bermuda, Bahia, fescue, Johnson grass, orchard grass, and ryegrass.
These grasses are everywhere: lawns, parks, roadsides, and open fields. Unlike trees, which finish pollinating relatively quickly, grasses release pollen over a longer window because different species bloom at slightly different times. In southern states, Bermuda grass can pollinate for much of the year, while cooler-climate grasses like Timothy and Kentucky blue tend to peak in June and July. Tree pollen from species like oak, elm, and mulberry can also linger into early summer, overlapping with grass season before tapering off.
Weed Pollen Starts in Late Summer
Just as grass pollen begins to ease, weed pollen picks up. Ragweed is the biggest offender, and its season typically starts in August and can last six to ten weeks, peaking in mid-September before dying off with the first hard frost. Other weeds that release pollen in late summer include pigweed, sagebrush, mugwort, lamb’s-quarters, cocklebur, and Russian thistle (tumbleweed).
This overlap between grass and weed pollen means that late summer, roughly August through September, can be the worst stretch for people sensitive to multiple types of pollen. If your symptoms seem to worsen or change character in August, ragweed is a likely culprit. A single ragweed plant can release up to a billion pollen grains, and the lightweight particles travel hundreds of miles on the wind.
When Pollen Counts Are Highest During the Day
Pollen levels aren’t constant throughout the day, which matters if you’re trying to plan outdoor activities. Research from the American College of Allergy, Asthma & Immunology found that pollen counts tend to be lowest between 4:00 a.m. and noon. Levels climb in the afternoon and peak between 2:00 and 9:00 p.m.
This pattern might surprise you if you’ve heard the common advice to avoid mornings. For grass and weed pollen specifically, afternoons and early evenings are typically worse. Hot, dry, windy days push more pollen into the air, while rain temporarily washes it out of the atmosphere. If you’re planning a run or time in the yard, earlier in the day is generally your better window during summer.
Regional Differences in Summer Pollen
Where you live significantly shapes your summer pollen experience. In warmer southern states, pollination can be nearly year-round, meaning there’s rarely a true break from pollen exposure. Bermuda grass, for example, pollinates across a much longer window in the Southeast and Gulf Coast than it does in the Midwest or Northeast.
Northern climates tend to have a more defined summer pollen season with a clearer start and end. However, that season is getting longer. EPA data shows that since 1995, ragweed pollen season has grown longer at 10 of 11 locations studied across North America. The biggest shifts have occurred at northern latitudes: ragweed season extended by 25 days in Winnipeg, 21 days in Fargo, and 18 days in Minneapolis between 1995 and 2015. Rising temperatures allow plants to start pollinating earlier and continue later, stretching the window of exposure.
Coastal areas sometimes offer modest relief because onshore breezes can push pollen inland, but this varies widely depending on local vegetation and wind patterns. Mold spores, which compound summer allergy symptoms for many people, peak in July in warmer states and persist year-round in the South and along the West Coast.
How to Tell if Summer Pollen Is Affecting You
Summer pollen allergies produce the same core symptoms as spring allergies: sneezing, runny or stuffy nose, itchy and watery eyes, and a scratchy throat. The difference is timing. If your symptoms start or worsen in June and July, grass pollen is the likely trigger. If they ramp up in August, ragweed or other weed pollens are more probable.
About one in four American adults has a diagnosed seasonal allergy, with women (29.9%) affected at higher rates than men (21.1%). Many people who think they “only have spring allergies” are actually reacting to grass pollen that carries into summer without a clear break. Allergy testing can identify exactly which pollens trigger your symptoms, which helps you anticipate your worst weeks rather than being caught off guard.
Reducing Your Exposure
Checking your local pollen forecast daily is the single most useful habit during summer. Most weather apps and sites now include pollen counts broken down by type, so you can see whether grass, weed, or tree pollen is elevated on a given day.
On high-count days, keep windows closed and use air conditioning instead. Shower and change clothes after spending time outdoors, since pollen clings to hair, skin, and fabric. If you’re mowing the lawn or doing yard work, that’s a direct, concentrated exposure to grass pollen, so wearing a mask during those tasks makes a real difference. Drying laundry outside on a line during summer pollen season effectively coats your clothes and sheets in the allergen you’re trying to avoid.
Timing outdoor exercise for the morning hours, when pollen tends to be lower, and avoiding windy afternoons gives you a practical edge. Over-the-counter antihistamines and nasal sprays are effective for most people when taken consistently rather than only after symptoms appear. Starting them before your known peak season keeps symptoms from building up.