Cherry Blossom Peak Bloom Forecasts Issued for 2018:
by Cherry Blossom Watch https://cherryblossomwatch.com
The two peak bloom predictions to watch are the ones from the National Park Service and the Washington Post‘s Capital Weather Gang. From time to time, others of note are issued and I’ll include them here.
National Park Service. At a press conference on March 1, the National Park Service issued their first peak bloom prediction for the 2018 season. They predicted that peak bloom would fall sometime between March 17 to 20. On March 12, they revised that prediction to March 27 to 31. On March 23, they pushed it back again to April 8-12. On April 3 they adjusted it again, to March 5-8.
Washington Post Capital Weather Gang. On February 27, the Washington Post‘s Capital Weather Gang posted their first peak bloom prediction of March 23 to 27, “centered on March 25.” Late on March 12, they posted a revised prediction of March 30 to April 3. On March 23, they revised it again, pushing it back to April 8-12, “centered on April 10.”
Common Questions 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 to this page for the current forecasts or signing up to get updates using one of the methods described below.
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 horticulturalists aren’t really comfortable with their predictions until about 10 days out.
What Does “Peak Bloom” Mean and Why Is It a Date Range?
The peak bloom date is the day on which the NPS horticulturalists judge that 70 percent of the Yoshino blossoms are out.
It’s 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 at some point 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 Accurate Are Peak Bloom Forecasts?
The NPS horticulturalists are the first to point out that they’re not really confident in their prediction until about 10 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 a month or more 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 they 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.
Are There Any Other Peak Bloom Forecasts?
The two to watch are the forecasts by the National Park Service and the Washington Post‘s Capital Weather Gang. Typically, the National Park Service one is put out first–usually around the beginning of March–followed by the Capital Weather Gang’s about a week later.
From time to time there are some other ones issued that are worth noting. I keep this page updated with the latest forecasts.
How Long Do the Flowers Stay Out? What if I Miss Peak Bloom?
The day the cherry blossoms reach peak bloom is not, of course, the only day you can see the flowers. At minimum, you can expect a beautiful sight for at least a few days before the peak bloom date and at least a few days after. Sometimes they can be out for a couple of weeks.
How long they’re out depends on weather conditions. In ideal conditions (cool, dry, calm), there can still be flowers to see a week or even more after the peak bloom date. In less-than-ideal conditions (wet, windy, hot, stormy), the flowers disappear more quickly. I’ve put together a timeline with photos from previous years to give an idea of what you can expect to see during the different stages of the bloom. And if you’d like to find out more about what peak bloom means I have a post on that.
The crucial point is that you don’t have to be there precisely on that specific day to be greeted with a beautiful sight. There are still flowers to see in the days before and after that.
If you’re too early for the main cherry blossoms, your timing might be good for magnolias. There’s a particularly beautiful collection of them in the garden behind the Smithsonian Castle.
And if you’re too late for the Yoshino peak bloom by two or three weeks, you might in luck for a different variety that is also very pretty: the Kwanzan cherry blossoms. Tulips are another spring highlight around the area.