The National Oceanic and Atmospheric Association just released their Winter 2015/2016 (December 2015-February 2016) temperature rankings which makes this the warmest winter on record for the continental U.S. (see temperature ranking map below). A record strong and well-advertised El Nino contributed to the warmth in the winter which had people and plants alike confused. In December, I witnessed cherry trees blossoming in southeastern Pennsylvania making it a 'Pink Christmas' instead of a 'White Christmas'. Those trees are about to blossom again as we enjoy record warmth in the East. The famous cherry trees in Washington D.C. are on the verge of developing green buds, and peak blossom will follow likely within the next 2 weeks.
As with any plant, the blossoming of the cherry trees in Washington D.C. is highly dependent on the weather. Given that we've had a record warm winter, it should come as no surprise that the cherry tree bloom is expected to be earlier than normal this year. The average peak blossom occurs sometime around April 1st to April 4th. This year, the National Park Service, who up until 2 days ago had a rather conservative (a.k.a. near normal) forecast of peak blossoming occurring around March 31st to April 3rd, has recently updated their forecast for peak blossom between March 18th and the 23rd. The last time the cherry trees blossomed this early was 4 years ago in 2012, which happened to coincide with the warmest February and March combined period of the past 25 years for the city of Washington D.C. (see chart below for average February-March temperatures for the past 25 years). This year, wt360 projects that D.C. will end up seeing the 3rd or maybe even the 2nd warmest February to March period in the past 25 years.
Very cold winters the past 3 years in D.C. have resulted in a later than normal blossom for the cherry trees. This year, spring has come early and so too will the cherry blossoms. The annual Cherry Blossom Festival runs unusually long, from March 20th to April 17th, so there should be plenty of beautiful flowers around for at least the beginning of the festival. However, if the peak blossom occurs any earlier than the 18th, there may only be a couple of days of being able to view the trees in full bloom during the festival.
Of course, the weather can make this period of full bloom slightly longer or shorter. Cool and calm weather extends the period of full bloom, while windy and stormy weather can shorten the bloom. High winds and wet weather will cause the petals to drop at a faster pace, and anyway, it's hard to enjoy an outdoor festival when it's raining. The unsettled weather pattern we're currently in across the U.S. looks set to continue over the next 2 weeks, so there's a good chance the peak bloom could be cut short this year.
My advice is if you want to see the cherry blossoms in Washington D.C. this year, plan to go early and don't expect a very large window of opportunity. Although, it shouldn't be too hard to get people in the mood to do spring-related activities as we enjoy above normal temperatures in the eastern United States.