On a hot summer day, you’ll often hear someone talk about how “humid” it is. But humidity doesn’t tell the whole story. How muggy a day feels also involves the dew point, the temperature to which the air must be cooled, at constant pressure, to be completely saturated. At that point, the relative humidity is 100%. That means the air can’t hold any more water in gas form. The higher the dew point, the more moisture in the air. And that directly affects how comfortable it feels outside. For example, if the temperature is 30 degrees and the dew point is 30 degrees, the relative humidity is 100%. But if the temperature is 80 degrees and the dew point is 60 degrees, the relative humidity is 50%. But think about it, that 80-degree day with 50% humidity will feel muggier than the 30-degree day with 100% humidity. The National Weather Service says here’s what you can expect at these dew points on a summer day: less than or equal to 55, dry and comfortable; between 55 and 65, becoming “sticky” with muggy evenings; greater than or equal to 65, lots of moisture in the air, becoming oppressive. WELL WEDNESDAY | Cooling Off In Summer With Allergies |  | Fans can distribute pollen and trigger allergies. (Patrick Pleul/picture alliance via Getty Images) | Summertime temperatures may have you reaching for the thermostat or a fan to cool down your home. But experts say fans and air conditioners could cause an increase in allergies and other uncomfortable symptoms. Fans can create flurries of dust, mold and pollen that make their way into your sinuses. A fan in a window can also pull pollen and other allergy triggers in from the outside. However, sleeping with a fan on might make some people more comfortable, especially if it blocks out noisy neighbors or cools off a room. Air conditioning units can also cause those same airborne allergens to circulate throughout the duct system in your home. It’s important to regularly maintain the HVAC system and change filters every 30 to 60 days. #OTD | 1972: Flooding From Agnes |  | | Fifty-one years ago today, former Hurricane Agnes began regaining strength. It became a tropical storm again over North Carolina and moved offshore Norfolk, Virginia. It continued to strengthen into a strong tropical storm and then swung back inland near the tip of Long Island. It merged with a second low pressure system over Pennsylvania soon after. Together, the combined storms dumped torrents of rain. The mid-Atlantic states had already seen an abnormally wet May, so the ground wasn’t able to soak up Agnes’ new rains. A large swath of more than 10 inches of rain fell from northern Virginia to the Finger Lakes of New York. The widespread flooding that resulted led to Agnes being called one of the most destructive hurricanes in U.S. history. It killed 122 people and caused billions in damage in 12 states. Damage was particularly high in New York, Pennsylvania, Maryland and Virginia. | | | | |