The cherry blossoms peaked on March 25 last year. (Kevin Ambrose)

(This report, first published at 12:15 p.m., was updated at 12:45 p.m. to include the National Park Service’s revised prediction, just in.)

The much colder-than-normal March weather has slowed the blooming of the cherry blossoms to a near halt. What once was expected to be an earlier-than-normal peak bloom now seems destined to make its appearance about 10 days late.

Our new projected peak bloom window is April 8 to 12, centered on April 10. This is 11 days beyond the recent 30-year average peak bloom date of March 31.

We had predicted a peak bloom date of April 1 and, before that, March 25. The National Park Service also revised its peak bloom forecast Friday, shifting it to from April 8 to April 12 from its earlier March 27 to March 31 (its original prediction was March 17 to 20). Our outlooks are now in perfect agreement.

Peak bloom, defined as when 70 percent of the cherry blossoms along the Tidal Basin are showing their colors, should still coincide with this year’s National Cherry Blossom Festival, which spans March 20 to April 15.

We can blame colder-than-expected March weather for the multiple forecast revisions. The temperature has averaged 3.5 degrees below normal so far this month. While we expected March to start off cold, the endurance of the chill has surprised us. Remarkably, the temperature has yet to hit 60 degrees this month. This is only the sixth time on record (since 1871) that temperatures have remained below 60 through March 22.

This March also featured 4.1 inches of snow on the 21st. However, the blossoms buds were not advanced enough to be damaged by the snow and frost.

In another odd weather note, while March has been colder than usual, Washington enjoyed eight days of 60-degree or warmer weather in both January and February. In fact, March has been colder than February overall.

The February warmth helped the blossoms get off to a super quick start, reaching the green bud phase, the first of five in the bloom cycle, on Feb. 25. But they’ve made little progress since. They reached the florets visible in the second phase on March 15 and are about to hit the third phase — the extension of florets. But they still need to pass through peduncle elongation and puffy white, the fourth and fifth stages, before peak bloom is declared.

On Thursday, the National Park Service announced the cherry blossom indicator tree had reached peak bloom, which normally signals the rest of the trees should peak in seven to 10 days.

But this year is anything but normal. The forecast for the next two weeks, on balance, again calls for cooler-than-normal weather. Still, we are likely to see a thaw in about five or six days bringing high temperatures near or above 60 at the tail end of March. This relative warmth would be good news for cherry blossom lovers.


European modeling system 15-day temperature forecast. (WeatherBell.com)

But what we don’t see ahead is an extended period of balmy temperatures into the 70s, which would accelerate the bloom process. In fact, there are signs that substantially cooler-than-normal temperatures will revisit the region in early April, with highs averaging in the low-to-mid-50s. Cold nighttime temperatures — forecast to dip into the 30s — would also keep the blossoms buds from bursting out earlier.

For these reasons, we think we probably won’t see Washington’s celebrated peak bloom until April’s second week. Our projection is informed by past years in which we had a mild February followed by a cold March, including:

  • 1932. February was 4 degrees warmer than normal, and March was 7 degrees colder than normal. Peak bloom occurred April 15.
  • 1952. February was 2 degrees warmer than normal, and March was 3.5 degrees colder than normal. Peak bloom occurred April 9.
  • 1954. February was 4.5 degrees warmer than normal, and March was 2 degrees colder than normal. Peak bloom occurred April 6.
  • 1973. February was 4 degrees warmer than normal, and March was 2 degrees colder than normal. Peak bloom occurred April 11.
  • 1984. February was 5 degrees warmer than normal, and March was 5 degrees colder than normal. Peak bloom occurred April 3.

(This past February was 6 degrees warmer than normal, and March is running 3.5 degrees colder than normal.)

Of course, if the cold air is more intense and lasts longer than expected, we may have to revise our peak bloom prediction one more time.

If peak bloom occurs on April 10, as we predict, it will be the third time in the last five years. Peak bloom also held off until April 10 in 2013 and 2014, both of which also had a colder-than-normal March.