Seasonal allergy symptoms include sneezing, a runny or congested nose, and itchy, watery eyes. They follow the pollen calendar: trees release pollen in spring, grasses in late spring and summer, and weeds like ragweed in late summer and fall, peaking around mid-September.
Seasonal allergy symptoms almost always trace back to one thing: the Pollen Calendar, the seasonal schedule that tells you which plants are releasing pollen and when. The symptoms themselves stay remarkably consistent from spring to fall, but the trigger rotates through trees, then grasses, then weeds. Learning the calendar is the single most useful framework for making sense of why you feel worse at certain times of year, and it lines up closely with when allergy season arrives in your area.
These reactions are collectively known as hay fever, or allergic rhinitis. The name is misleading: hay fever has nothing to do with hay or fever. It is an immune reaction in which the body treats harmless pollen proteins as a threat, not an infection. If you want the biological background, our overview of what pollen is covers how these tiny grains set the whole process in motion.
Symptoms by Pollen Season
Whether it is spring tree pollen or fall ragweed, the symptoms look the same because the underlying immune response is the same. Across every season, the classic signs of allergic rhinitis are:
Sneezing and a runny or congested nose
Itchy, watery, or red eyes (allergic conjunctivitis)
Itching in the nose, palate, or throat
Postnasal drip and cough
Fatigue that can drag on for weeks
For some people, seasonal pollen can also trigger or worsen asthma and aggravate eczema. One thing seasonal allergies do not usually cause is a true fever, despite the "hay fever" label. A genuine fever, body aches, or thick discolored mucus point more toward a cold or sinus infection than an allergy. Our guide to pollen allergy symptoms breaks these signs down in more detail.
Trees, Grass & Ragweed Timing
Here is the heart of the Pollen Calendar. Different plants pollinate at different times of year, so if you are sensitive to more than one type, you may notice several stretches of symptoms rather than a single season. Trees come first in spring, grasses take over in late spring and summer, and weeds finish the year in late summer and fall.
The Pollen Calendar — Season by Season
Pollen Source
🌿 When It Peaks
📋 What to Know
Trees
Spring
The first wave of the year; the earliest seasonal flare-ups.
Grasses
Late spring & summer
Takes over as tree pollen fades and warm weather sets in.
Weeds (ragweed)
Late summer–fall, peak ~mid-September (Aug–Nov)
One plant can release up to 1 billion pollen grains; a grain can travel over 100 miles.
Symptoms stay the same across the year; only the pollen source rotates from trees to grasses to weeds.
Ragweed deserves special mention. A single ragweed plant can produce up to one billion pollen grains in a season, and a single grain can travel more than 100 miles on the wind. That is why fall symptoms can appear even if no ragweed grows near your home. Ragweed season generally runs from August into November and peaks around the middle of September.
Managing Seasonal Flare-Ups
Because the symptoms are driven by exposure, the most reliable strategy is to reduce contact with pollen during your trigger season. Practical steps include:
Staying indoors and keeping windows closed on high-pollen days
Using a HEPA filter indoors
Showering and changing clothes after time outside to remove pollen
Timing outdoor activity to avoid the morning pollen peak
A pollen count measures the number of pollen grains per cubic meter of air and is reported as low, moderate, high, or very high on the National Allergy Bureau scale. The thresholds differ by pollen type, and the higher the count, the more likely you are to have symptoms, so a daily forecast is a useful planning cue. Beyond exposure control, options range from oral and nasal antihistamines to corticosteroid nasal sprays and allergen immunotherapy, which are worth discussing with an allergist. For a fuller look at the choices, see our guide to allergy relief.
When to See a Doctor
Seasonal allergies are usually manageable, but an allergist can confirm your triggers and guide treatment. Consider seeing a doctor if any of the following apply:
Symptoms are severe, last for weeks, or disrupt sleep and daily life
You have a true fever or symptoms that suggest a sinus infection rather than an allergy
Pollen appears to trigger or worsen asthma or eczema
You want a formal diagnosis through a skin-prick test or specific IgE blood test, or are considering immunotherapy
This page is informational only and is not a substitute for personal medical advice.
Frequently Asked Questions
What are the main symptoms of a seasonal allergy?
Seasonal allergies, also called hay fever or allergic rhinitis, typically cause sneezing, a runny or congested nose, and itchy, watery, or red eyes. Many people also notice itching in the nose, palate, or throat, postnasal drip, cough, and fatigue. These are the same symptoms across every pollen season; only the timing changes depending on whether trees, grasses, or weeds are releasing pollen.
Do seasonal allergies cause a fever?
No. Despite the name hay fever, seasonal allergies do not usually cause a true fever. Hay fever is an immune reaction to harmless pollen proteins, not an infection. A real fever, body aches, or thick discolored mucus point more toward a cold or sinus infection than an allergy. If you run a fever, it is worth considering a non-allergic cause.
When is ragweed season?
Ragweed and other weeds are a late-summer to fall problem. Ragweed pollen generally runs from August into November and tends to peak around the middle of September. A single ragweed plant can produce up to one billion pollen grains in a season, and a single grain can travel more than 100 miles on the wind, so symptoms can appear even where no ragweed grows nearby.
Why do my allergy symptoms change through the year?
Your symptoms shift because different plants pollinate at different times. Trees release pollen in spring, grasses in late spring and summer, and weeds such as ragweed in late summer and fall. If you are sensitive to more than one type of pollen, you may notice flare-ups in several stretches of the year rather than one single season.
How can I reduce seasonal allergy flare-ups?
Reducing exposure helps most. On high-pollen days, stay indoors when you can, keep windows closed, and use a HEPA filter. Pollen counts are often highest in the morning, so plan outdoor time accordingly. Showering and changing clothes after being outside removes pollen from your skin and hair. Medications and allergen immunotherapy are also options to discuss with an allergist.
How do I read a pollen count?
A pollen count measures the number of pollen grains in a cubic meter of air and is reported as low, moderate, high, or very high on the National Allergy Bureau scale. The thresholds differ by pollen type, so a high grass count and a high ragweed count are not the same number. The higher the count, the more likely you are to have symptoms, so it is a useful cue to limit time outdoors.
Are seasonal allergies the same as a cold?
No. Seasonal allergies usually bring no fever, clear nasal discharge, itchy eyes, and symptoms that last for weeks and start suddenly when you are exposed to pollen. A cold may cause a mild fever and body aches, produces thicker mucus, clears in about 7 to 10 days, and is contagious. The itchy, watery eyes are a strong clue that you are dealing with an allergy.
Sources
ACAAI — Ragweed Allergy (weed season late summer–fall, peak ~mid-September; one plant up to 1 billion pollen grains; a grain can travel over 100 miles).
ACAAI — Allergy Facts (pollen seasons: trees in spring, grasses in late spring/summer, weeds in late summer–fall).
Mayo Clinic — Hay fever (allergic rhinitis) (symptoms, immune reaction to pollen, no true fever, exposure reduction and treatment).
AAAAI — Pollen Counts Defined (pollen count = grains per cubic meter of air; low/moderate/high/very high on the National Allergy Bureau scale).
AAFA — Pollen Allergy (exposure reduction, HEPA filtering, and links to asthma and eczema).