How Climate Patterns Are Changing Allergy Seasons Year Over Year

How Climate Patterns Are Changing Allergy Seasons Year Over Year

Since 1850, the Earth’s global temperature has increased by about 0.11°F per decade. Since the early 1980s, the rate has accelerated to an average of 0.36°F per decade. Since records have been kept, 2024 was named the warmest year on record. In fact, 10 of the warmest years on record occurred after 2014.

As the Earth’s core temperature changes, weather patterns shift. Higher temperatures accelerate evaporation, which can cause droughts that fuel wildfires. In some areas, the evaporated moisture accumulates in the air, leading to flooding rains. All of this affects allergy seasons in different ways.

Central California’s Geography Impacts Allergy Seasons

Before you even consider the impact of climate change, the region around Fresno is already known for its allergens. Central California avoids Southern California’s coastal humidity and smog. However, it’s known as California’s “Allergy Epicenter” because of its geography and a strong agricultural industry. 

Much of Central California lies within the Sacramento-San Joaquin River Delta, the Sierra Foothills, and the San Joaquin Valley. When you consider Central California’s geography alongside climate change, it creates a perfect storm for allergies. 

Fresno, the fifth-most populous city in California, has many residents who commute daily. It is located just under 310 feet above sea level, an important detail considering the area’s topography.

• Kings Canyon National Park, to the east, ranges from 1,370 to more than 14,000 feet above sea level.
• Sequoia National Park lies to the southeast, and it rises to almost 13,000 feet above sea level.
• The 225-acre Kearney Park lies to the west and is 200 to 300 feet above sea level.
• Yosemite National Park is northeast of the city and ranges from 2,000 to over 13,000 feet above sea level.

Fresno’s low elevation situates it in a valley where hot air accumulates throughout the summer, while winters stay mild. Approximately 81% of the year is sunny. Winds typically blow from the northwest, although a few months see a shift to southeastern winds.

The combination of low elevation and warm pockets of air at valley height intensifies pollen, wildfire particles, and pollutant concentrations, increasing allergy risk. Warmer winters and dry summers worsen allergies.

The Impact of Longer and Warmer Growing Seasons

One of the biggest problems with warmer weather and changing climate patterns is that growing seasons are extending. Trees flower earlier than usual. Plants that require drier or hotter weather start to thrive in regions that have never been able to support them before. It introduces more and newer pollen to the air. 

Home gardeners might be tempted to plant things they’ve never successfully grown before. Not only does that introduce new pollen into the air around them, but plants like pampas grass or Italian thistle also provide fuel for wildfires. Invasive plants also grow faster and overtake native plants, reducing food supplies.

Central California’s Three Main Allergen Sources

Olive, juniper, and oak trees are three primary sources of plant pollen in spring and summer’s heat. Russian olive is an invasive tree that drowns out native plants, so it’s advised to keep it out of your yard. Oak and juniper are prevalent in the surrounding parks and forests, and their pollen is a leading cause of spring allergies.

Fresno has one other allergen to consider. California produces about 80% of the world’s almonds and 100% of the U.S. commercial supply. Fresno is directly responsible for around 25% of that. 

Almond pollen is heavy and sticky. The pollination season typically lasts more than a month, extending from the first flowers in late January into March. Almonds grow over the summer and are usually harvested in August. Climate change is affecting this. Trees used to flower in February, but some farmers are seeing the first blooms in January.

The pollen from almond blossoms does cause allergies in some people, and symptoms range from a runny nose and stuffiness to sneezing and itchy, watery eyes. In more severe cases, a person might experience asthma-like symptoms. 

Although Fresno County is still in a mild drought, there has been more rain in recent months. This ensures trees will flourish in the spring, worsening allergies.

Droughts and Their Dusty Conditions

Fresno is no stranger to drought conditions. While November 2025 was the fifth wettest November in history, an extreme drought occurred from 2014 to 2017. Extreme droughts also occurred in 2021, 2022, and 2023.

During these droughts, dusty conditions increase. That dust carries pollen, pesticides, pollutants, and other irritants that exacerbate allergies in susceptible people. PM10 is a large dust particle that irritates the respiratory system. 

Particulate matter (PM) consists of airborne particles of various sizes. PM10 refers to particles no larger than 10 micrometers. The smaller the number following PM, the tinier the particle. When you breathe them in, they enter your airway and irritate the lining of your sinuses, throat, and lungs.

Because PM10 particles are larger, they are also heavier and settle on surfaces in your home and on the ground more quickly. However, they are not as large as you might think. The average human hair diameter is 70 to 80 micrometers. Examples of PM10 include ash from burning wood, construction dust, mold spores, and dust from fields or unpaved roads.

The dustier your home, the more dust mites you may have living in your carpets, mattresses, and upholstery. Mold and pollen spores, pet dander, and your own dead skin feed dust mites. As they feed on the particles in your dust, they leave microscopic feces and their own dead bodies behind. That can trigger dust mite allergies in some people.

Solutions That Ease Allergy Symptoms

When you deal with seasonal allergies or experience year-round symptoms from dust, mold, or pet dander, relief is essential. It’s hard to function at work, in social activities, or at school if your sinuses are stuffed, your eyes are itchy, or you can’t stop sneezing.

An allergist works with you to find a solution that eases your symptoms and teaches your immune system to lessen its response. Medications might help, but there are other options. Instead of allergy flare-ups, you could have minimal symptoms over time. 

Immunotherapy is an option that helps minimize allergic reactions and makes it easier to go about your usual routines. You’re exposed to small amounts of your allergen over time to help your immune system learn not to overreact. 

It’s offered through weekly allergy shots for several years, three monthly allergy shots given directly into a lymph node, or sublingual drops or dissolvable tablets that you place under your tongue each day for several years.

You don’t have to stay indoors and avoid nature. You don’t have to keep a 24/7 air purifier near you to breathe easily. Our allergist conducts allergy tests and discusses the best options for complete relief. Schedule an appointment with Premium Allergy & Respiratory Center to learn more about the allergens affecting your quality of life and the treatments that help.