By Rick Kincel
Technical Services, Coburn Supply
As temperatures climb each summer, the public conversation inevitably turns to the sticky, oppressive feel of the air. Most people attribute this discomfort to relative humidity, but there’s a more accurate and telling measure: dew point. And it’s trending in a troubling direction.
Why Dew Point Matters More Than Relative Humidity
Relative humidity (RH) is a commonly cited metric, but it’s largely misunderstood. RH depends on temperature — it rises when the air cools, even if the moisture level remains unchanged. For example:
- At 80°F and a 55°F dew point, RH is 42%
- At 75°F, RH rises to 50%
- At 70°F, it climbs to 59%
In all cases, the actual moisture in the air — represented by the 55°F dew point — has not changed. What has changed is how saturated the air is relative to its temperature. This is why dew point is a more consistent and practical indicator of humidity discomfort.
Dew Point on the Rise: A Look at the Data
Over the past 85 years, dew point levels have steadily increased. In fact, 2024 recorded the highest average dew points on record — a worrying trend for comfort, energy efficiency, and structural health in buildings.
During the humid months between May 1 and September 30, locations like Galveston, New Orleans, Biloxi, and Miami regularly reported high dew points well into the “oppressive” range. More importantly, their average dew points stayed above 70°F, a threshold where many begin to feel “very humid and uncomfortable” outdoors.
| City | High Dew Point (°F) | Average Dew Point (°F) |
| Galveston, TX | 84 | 73 |
| New Orleans, LA | 83 | 74 |
| Biloxi, MS | 82 | 73 |
| Miami, FL | 81 | 74 |
| Daytona, FL | 81 | 74 |
| Chicago, IL | 79 | 58 |
| Newark, NJ | 77 | 60 |
While northern cities like Chicago and Newark do occasionally hit high dew points, their average values fall significantly throughout the summer. This allows buildings in those areas to dry out periodically, maintaining better indoor comfort and preventing excessive moisture buildup.
Moisture’s Hidden Impact on Homes
In consistently humid climates, high dew points prevent buildings from drying out — a key factor in long-term comfort and home health. A persistently high dew point increases indoor moisture levels, impacting not just comfort but also HVAC system efficiency and building materials.
Rather than relying solely on air conditioning to lower indoor temperatures — and by extension relative humidity — homeowners should target dew point control.
A Whole-Home Solution: Dehumidification is No Longer Optional
Maintaining an indoor dew point at or below 55°F is crucial in humid climates. The most effective solution? A whole-home dehumidifier, like those offered by Ultra Aire. Once considered a luxury, these systems are now an essential component for managing indoor air quality and preventing moisture damage.
As climate patterns shift and moisture levels continue to rise, dew point awareness will become increasingly vital. Homeowners, contractors, and HVAC professionals must adjust their approach — focusing on managing dew point rather than just lowering temperature — to ensure year-round comfort and energy-efficient living.