If you think this summer has felt extra sticky and sweltering hot in Ohio and Kentucky, you’re not alone.
Greater Cincinnati has spent much of the summer trying to stay cool, as the area has been battered with heat advisories.
“We’ve had a much more humid summer than usual,” Owen Shieh, a meteorologist with the National Weather Service’s Weather Prediction Center, told USA TODAY.
In July, 18 states across the United States, including Ohio and Kentucky, experienced their most humid July since records began in 1981, Ben Noll, global weather writer and meteorologist for The Washington Post, reported.
So what’s causing the humidity? Will it continue? Here’s what to know.
What other states experienced record-breaking humidity in July?
Several other states also experienced record-breaking humidity in July. According to Cameron Lee, a climate scientist and associate professor at Kent State University, parts of the northeastern United States have had some of their highest humidity levels on record.
The dew point for much of the East has been five to seven degrees greater than average, Lee said. The dew point is the measure of how much water vapor is in the air. The higher the temperature, the greater the amount of moisture.
“We’re in rarified territory,” Lee told USA TODAY.
Another measure of humidity is the overnight minimum temperature. According to Shieh, many major cities throughout the eastern United States, including Baltimore, Washington, D.C., and Philadelphia recorded some of their highest overnight temperatures in history.
Below is the list of states that felt the humidity of summer.
What is contributing to higher humidity?
The reason it’s been so sticky out is due to the Bermuda-Azores high-pressure system.
This semipermanent dome of fair summer weather typically sits over the central Atlantic, but it has been further west than normal this summer, bringing hot and humid southerly winds to the central and eastern states, according to ForecastWatch, a weather forecast monitoring company based in Columbus.
Since air rotates clockwise around high-pressure systems in the Northern Hemisphere, this pushes hot and humid southerly winds across central and eastern states, per The Washington Post.
Above-average ocean temperatures across the western Atlantic and Gulf of Mexico have also added more moisture to the equation. All of these factors are “pushing this summer’s climate in a warmer and more humid direction,” The Washington Post reported.
ForecastWatch also stated that as the Earth becomes more humid and warmer due to climate change, the average dew point is expected to continue to rise, as it has over the past few decades.
Is climate change increasing humidity?
Fans attempt to cool off by the mist zone to beat the heat during the Cincinnati Open tennis tournament.
Along with the stagnant air, experts say climate change is a factor in the higher-than-average dew points, leading to days-long bouts when people are contending with rare humidity levels.
“It’s the extreme days that are increasing,” Lee, whose research focuses on climate change, told USA TODAY. “The days when dew points are in the 95th and 99th percentile are becoming more frequent.”
What is the difference between the dew point and humidity?
Humidity is more than just one concept. It includes absolute humidity and relative humidity.
Absolute humidity measures the actual amount of water vapor in the air, regardless of the air’s temperature, according to the Weather Service. On the other hand, relative humidity measures water vapor and its relativity to the temperature of the air.
As mentioned above, the dew point is the temperature at which the air must reach before it can be cooled, at constant pressure, to achieve a relative humidity of 100%.
Relative humidity and the dew point work together and have an impact on clouds and precipitation, says the Weather Service.
When relative humidity is at 100%, (such as when dew point temperature and actual air temperature are the same), this means there is a maximum amount of moisture present in the air at that particular temperature. As a result, this saturation could lead to fog, dew, clouds and, in other cases, precipitation.
In order for precipitation to occur, the air must no longer be able to support the weight of the suspended water droplets, causing precipitation to fall from the clouds, according to the Weather Service.
USA TODAY reporters Christopher Cann and Olivia Munson contributed to this report.
This article originally appeared on Cincinnati Enquirer: Yes, Ohio’s humidity has been bad this summer. Here’s why