U.S. Top 5 States That Struggle Most With Humidity—and How to Handle It

For a majority of Americans, the summer of 2025 was marked by oppressive humidity. According to The Washington Post, July of that year became the wettest July on record in 18 U.S. states, with record-breaking rainfall triggering deadly floods. However, while public attention focused heavily on flood-related news, the real “battle against moisture” for millions of households had only just begun. Even areas not directly hit by floods must contend with persistently high humidity across many U.S. states.

AlorAir, with over a decade of experience, is a leading provider of air management solutions, serving more than 1.2 million customers across North America with professional-grade equipment.

The Hidden Threat Behind High Humidity and Flooding

According to the U.S. National Library of Medicine, the ideal indoor relative humidity range is between 40% and 60%. Levels outside this range—whether too high or too low—can be harmful.

When relative humidity reaches 60% or higher, it creates an environment where mold, allergens, and dust mites thrive. These can trigger illnesses such as asthma and skin irritation. Damp conditions also attract pests—including termites, ants, and cockroaches—that hide in corners of the home, causing both health issues and structural damage.

Over time, high humidity can cause wood rot, peeling and blistering walls, rusting metal components. Additionally, moisture can damage electronics and ruin valuables such as books, musical instruments, and other sensitive items.

The 5 States with the Highest Annual Humidity in the U.S.

According to a report from the National Centers for Environmental Information (NCEI), the five most humid states in the United States are:

• Alaska (77.33%)

Cold air has a lower capacity to hold water vapor, leading to higher relative humidity readings, especially in coastal areas.

• Florida (74.47%)

Surrounded by water on three sides, the peninsula experiences high temperatures, humidity, and hurricane seasons. High moisture levels and seasonal heavy rainfall ensure that water vapor content in the air remains consistently high.

• Louisiana (74.25%)

Located on the northern coast of the Gulf of Mexico, the state receives large amounts of warm, moist air masses. The New Orleans area, in particular, faces dual humidity challenges due to its below-sea-level location.

• Mississippi (73.5%)

Similarly influenced by warm, humid airflow from the Gulf of Mexico, its climate mirrors Louisiana’s in many respects.

• Michigan (72.19%)

While classified as having a temperate continental climate, the state is significantly affected by the Great Lakes (especially Lake Michigan and Lake Huron). Winters are cold and snowy, while summers are warm and humid, with humidity levels consistently above 70% from June to August.

Compared to other states, residents in these areas must take proactive steps to mitigate the ongoing impact of high humidity on daily life, health, and home environments.

Region-Specific Solutions: Tailored Approaches to Humidity Challenges

Residents in each state adopt various strategies to maintain optimal indoor humidity levels (between 40% and 60%), reducing health risks and protecting their homes from damage:

1. Alaska

Alaska is in cold coastal climate with high relative humidity. The primary risk is condensation of warm indoor moisture on cold surfaces, leading to mold growth and wood rot. Homes feature thick insulation, require airtight construction, and often include basements or raised foundations. Therefore, residents need to focus on condensation prevention, enhanced insulation, and robust ventilation. Here are some recommended solutions:

• Mechanical Ventilation with Heat Recovery (HRV/ERV): In extreme cold, opening windows for ventilation causes major heat loss. HRVs (Heat Recovery Ventilators) or ERVs (Energy Recovery Ventilators) bring in dry outdoor air while pre-warming it with heat from exhausted indoor air. This prevents condensation on windows and walls while keeping temperatures stable.
• Comprehensive Vapor Barriers: A vapor barrier must be installed on the interior side of insulation to keep warm indoor moisture from penetrating walls and condensing inside cold structural elements.
• Use of Dehumidifiers: In damp, low-temperature areas like basements, dehumidifiers should maintain 40–50% humidity. Choose models designed for cold environments. For example, the AlorAir Storm LGR Extreme Dehumidifier includes auto-defrost and continuous drainage features that prevent coil freezing, ensuring reliable performance even in cold conditions (33–102°F).

2. Florida

Florida experiences a hot and humid coastal climate characterized by high temperatures, significant humidity, and annual hurricane threats. These conditions create substantial risks for homes, including persistent mold growth, accelerated corrosion, and potential structural damage due to prolonged moisture exposure and storm impacts. Therefore, effective moisture management, hurricane-resilient construction, and continuous ventilation are essential. Key strategies include:

• High-Capacity Dehumidification: Use industrial-grade dehumidifiers for garages, basements, and living areas.
• Enhanced Air Sealing and Moisture Barriers: Protect against storm-driven humidity intrusion with advanced sealing techniques and waterproof membranes.
• HVAC and Ventilation Optimization: Ensure AC systems are appropriately sized and maintained for humidity control. Supplement with ERVs for energy efficiency and balanced ventilation. The AlorAir Sentinel WHD 150 whole-house dehumidifier delivers high performance with a capacity of 140 pints per day (PPD), specifically designed for whole homes, crawl spaces, basements, and even commercial environments. It effectively reduces dust mites and mold spores, significantly improving indoor air quality.

AlorAir Sentinel WHD 150 whole-house dehumidifier (Photo source: AlorAir)

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3. Louisiana

Louisiana’s climate is defined by warm Gulf air, frequent flooding, and high groundwater levels. These elements contribute to elevated humidity, which fosters mold, insects, and material degradation in homes. As a result, solutions must emphasize flood resilience, continuous drainage, and persistent moisture control. Recommended measures include:

• Sump Pumps and Drainage Systems: Install reliable sump pumps with battery backups and perimeter drains.
• Whole-House Dehumidification: Connect whole-house dehumidifiers to HVAC systems for consistent humidity control.
• Elevated Construction and Water-Resistant Materials: Build raised foundations and use materials resistant to mold, such as closed-cell spray foam and tile.

4. Mississippi

Mississippi shares a similar climate with Louisiana, featuring high humidity, seasonal storms, and moisture-saturated air from the Gulf. These factors pose ongoing challenges to building integrity and indoor air quality. A combined approach of ventilation, drainage, and moisture management is essential. Consider implementing the following:

• Graded Landscaping and French Drains: Direct water away from foundations.
• HVAC with Dehumidification Mode: Use AC units with dehumidification settings or standalone units for comfort.
• Routine Maintenance and Mold Inspections: Regularly check crawl spaces, attics, and basements.

5. Michigan

Michigan’s climate is greatly influenced by the Great Lakes, resulting in cold, snowy winters and humid summers. Common risks include condensation, frozen pipes, and summer mold growth. To address these issues, year-round humidity control, thermal protection, and ventilation are crucial. Effective solutions consist of:

• HRV/ERV Systems: Manage indoor moisture from cooking, showers, and breathing in winter, and reduce incoming humidity in summer.
• Basement and Crawl Space Encapsulation: Seal below-grade areas to block moisture ingress.
• Smart Thermostats and Humidity Sensors: Use Wi-Fi-enabled devices to monitor and adjust conditions remotely.

Experts predict that humidity-related home insurance claims will rise by over 35% in the next five years. Investing in professional moisture solutions today not only safeguards your immediate health but also protects your most significant financial asset—your home.

Facing diverse and complex humidity challenges, choosing the right solution is key to winning the “battle against home moisture.” As a professional provider of dehumidification solutions, AlorAir offers efficient, reliable products tailored to regional needs.

Visit the official AlorAir website or contact us today to find your professional dehumidification solution and protect your family’s health and comfort. At AlorAir, we care about your air.