“When will the cherry blossoms finally open?” As someone working at a hotel in Hakodate, this is by far the most frequent question I receive this time of year.

Did you know that there is actually a mathematical formula used to predict the bloom? Today, let’s dive deep into the 2026 forecast for Hakodate (April 24th) using a bit of “Sakura Science.”

1. The Magic Number: What is the “600°C Rule”?

Among weather enthusiasts in Japan, there is a famous principle known as the “600°C Rule.”

The rule is simple: “If you add up the daily maximum temperatures starting from February 1st, the cherry blossoms will bloom on the day the total exceeds 600°C.”

The Formula : ∑(Daily Max Temp from Feb 1st)≥600℃

In cold regions like Hakodate, temperatures stay low through February and March. However, once April arrives and the mercury rises, the countdown to that “600°C” mark accelerates rapidly.

2. Historical Data: A Look at Hakodate’s Past Blooms

Let’s look at the recent data for Hakodate. While we’ve seen record-breaking early blooms over the past few years, 2026 seems to be returning to a more traditional schedule.

Year	First Bloom	Full Bloom	Notes
2023	April 14	April 20	Earliest on record
2024	April 18	April 23	Early
2025	April 18	April 22	Consistent early bloom
2026(Est.)	April 24	April28	Returning to average

The April 24th forecast suggests that we had a slightly colder February and March, or perhaps a more gradual arrival of spring this year.

3. What to Expect for Golden Week 2026?

Based on this year’s forecast, here is how the Sakura schedule is shaping up for our holiday season:

• First Bloom (Around April 24): The first few blossoms appear on the “sample tree” at Goryokaku Park.
• Full Bloom (April 28 – May 2): The absolute peak! The blossoms will be at their most beautiful during the first half of Golden Week.
• Petal Blizzard (May 3 – May 5): The “Hana-ikada” (flower carpets) will fill the moats. A stunningly poetic end to the season.

It looks like 2026 will be the perfect year to spend your Golden Week surrounded by cherry blossoms!

Closing Thoughts

Nature is unpredictable, and these dates can shift by a few days depending on the weather in the coming weeks. I’m checking the temperature charts on my PC every day with excitement. Why not try adding up the temperatures yourself and make your own prediction for your visit?

Enjoy every moment of your Hakodate journey, and travel safe!