At a press conference this morning, the arborists at the National Park Service revealed their initial peak bloom prediction for 2020.
They said that they expect DC’s cherry blossoms to reach peak bloom sometime between March 27 and 30.
The Washington Post‘s Capital Weather Gang issued their prediction yesterday, forecasting a peak bloom between March 25 and 29. And NBC’s Storm Team4, a new player in the peak bloom prediction game, predicts March 18 to 23.
It’s worth emphasizing that these are initial peak bloom predictions, and it’s not unusual for them to be tweaked or changed as we get closer. That’s largely because they rely on weather forecasts looking a few weeks ahead. And as we all know, those kinds of forecasts don’t always pan out quite as expected.
You can find some more photos that I took this morning in today’s update. It includes some shots of the indicator tree just starting to flower.
If you’re coming in from out of town, I’ve put together on some ideas on where to stay.
Common Questions About the Cherry Blossom Peak Bloom Forecasts
Here are some answers to some of the common questions I get asked about the cherry blossom peak bloom forecasts.
Do the Peak Bloom Predictions Change?
Yes. It’s common for them to be revised as we get closer to the bloom. Which is why it’s worth checking back for the current forecasts.
How Accurate Are the Cherry Blossom Peak Bloom Forecasts?
The NPS horticulturists are the first to point out that they’re not really confident in their prediction until about ten days out. And nature has a way of being unpredictable sometimes, as the 2017 bloom proved. There are so many variables that can come into play, especially since the prediction is based on long-range weather forecasts several weeks (or longer) out.
Sometimes, the predictions nail it. Other times, Mother Nature has other plans, and it’s not at all unusual for the forecasts to be revised as we get closer to the date as the actual weather conditions diverge from the long-range weather forecast the peak bloom predictions initially relied on.
So the peak bloom forecasts are the best information we have to go on, but that doesn’t mean things always pan out as expected, and it’s quite common for the forecasts to change. So be sure to keep checking in for any updates. I keep the peak bloom forecasts page up to date with the latest information.
What Does “Peak Bloom” Mean and Why Is It a Date Range?
The peak bloom date is the day on which the NPS horticulturists judge that 70 percent of the Yoshino blossoms are out. There are a number of different varieties of cherry trees around and near the Tidal Basin, but the Yoshino variety is by far the most numerous and famous.
“Peak Bloom” is a specific day that the threshold is passed. So when a forecast expects peak bloom between such and such dates, it means that they expect the 70 percent threshold to be crossed one day during that range.
It does not mean that the flowers will be at peak bloom for that entire date range. It also does not mean that you have to be there only on that specific day to catch the spectacle—more on that below.
I have more detail in a separate post explaining the ins and outs of peak bloom.
How are the Peak Bloom Predictions Made?
There are three parts that go into the mix for making the NPS peak bloom predictions. The first is a mathematical model that basically assigns heat points for temperatures. Once the trees wake up from their winter dormancy, there are thresholds for a certain number of heat points to bring them to bloom.
The second is actually looking at the trees to see how they’re developing. Sometimes the mathematical model doesn’t match what they’re actually seeing on the trees, as happened in 2018 when the model predicted a much earlier bloom than ended up happening because the buds got stuck in the green bud stage for much longer than expected.
The third part, and the most unstable element of the whole thing, consists of weather forecasts looking weeks ahead. We all know only too well just how unreliable forecasts that far ahead can be, and that’s the main reason that the peak bloom predictions can change quite a lot and why the NPS horticulturists aren’t really comfortable with their predictions until about 10 days out.
At this time of year, there are beautiful flowers to be had all over the place. Maybe in your backyard. Maybe in the local park.
These are ere are some of my favorite books that I've reviewed on taking photos of flowers: