Last year it hit 30 degrees for the first time on June 17, and the year before on June 26. The earliest tropical day of a year was May 9, 1976. On average, it will be 30 degrees for the first time on June 29. Since 1994 there have been one or more tropical days in De Bilt every year. On average there are five, but last year it was just one. In 2020 there were twelve and the record year is 1976. Then there were fourteen.
It’s official: De Bilt measures the first tropical day of the year
