Plot Description:

This chart presents the last date of fall or first date of spring that a given temperature threshold was last or first reached. Note that leap day creates some ambiguity with an analysis like this, so for example, the 15th of November is considered equal for each year. The plot truncates once you reach the 20th of December. If you use the downloaded file, please note that you need to consider the levels above the given threshold as the latest date. The downloaded file simply provides the latest date at a given temperature.