January 1932:
Whence and why this warm weather in January? Trite summer greetings that were supposed to be safely moth-balled and hibernating have been heard on every hand this week. Announcement of flowers blooming in the backyard, speculation as to whether swelling buds will ruin fruit prospects alternate with jovial remarks about getting out linen suits and limbering up the electric fans. Perspiring days to mid-January are even more unusual for Washington than snow-blockaded presidential inaugurations in March.
Source: “Tropical Washington,” The Washington Post January 16, 1932.
Highest temperatures for select cities:
Boston: 69°, 1/14
New York City: 70°, 1/14
Philadelphia: 73°, 1/14
Washington, DC (DCA): 77°, 1/15
January 1950:
Another flower at the Brooklyn Botanic Garden yesterday took advantage of the absence of wintry weather. A species of Adonis, with flowers, somewhat like a marsh marigold’s, joined the snowdrops in bloom along the main walk.
Source: “Adonis Flowers Come Out Weeks Early in Brooklyn,” The New York Times, January 24, 1950
Highest temperatures for select cities:
Boston: 72°, 1/26
New York City: 72°, 1/26
Philadelphia: 74°, 1/26
Washington, DC (DCA): 79°, 1/26
January 2007:
Around the city, there were signs of a season out of whack, like cherry blossoms in Central Park…
Source: Anthony Ramirez, “With Mild Winter, the City Revisits Fall Fashion and the Record Books,” The New York Times, January 6, 2007.
Highest temperatures for select cities:
Boston: 69°, 1/6
New York City: 72°, 1/6
Philadelphia: 73°, 1/6
Washington, DC (DCA): 73°, 1/6

Boston Public Garden (January 13, 2007)