the atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense and dew can form.
More details in this Wikipedia article
On Thursday, dew point values rose into the 60s as far north as the mid-Atlantic, and the 50s into parts of New England, making it feel unusually humid as well. The actual air temperature has reached into the 80s as far north as parts of eastern Virginia Thursday afternoon.
(Source: Record Warmth Expected Through Christmas Day and Beyond as Mild Weather Pattern Engulfs the East, Midwest from weather.com)
And wishing a very Merry Christmas to everyone who's celebrating it today! To those not celebrating--have a great Friday and enjoy the weekend!