Was there ever February 30th

February 30th: The day that only existed once

For fear of lost life and the turmoil of the Great Northern War, the year 1712 in Sweden and Finland was suddenly a 30th February longer.

"Peter is off on February 30th, so he doesn't care about the weather." While folk weather rules usually try to predict sun, rain and snow every year, these rules only applied once in two countries. Because Sweden and the dependent Finland (but not in the Swedish provinces on German territory) experienced a 30-day February in 1712. This is evident from entries in church registers. The reasons for the Unikum: hesitation and war.

When October 4th is followed by the 15th

In 1582 Pope Gregory XIII. the deletion of ten days, because the imprecise counting method on which the current Julian calendar was based had made the year ten days longer over the centuries (see info box below). To remedy this mistake, Gregor immediately followed October 4th (a Thursday) on Friday, October 15th.

While Spain, Portugal, the Catholic parts of Italy and Poland immediately put the requirements into practice, parts of southern Germany took their time with the conversion until 1583. Prussia even waited until 1612, Denmark and Norway until 1700, Turkey until 1927. The problem: The later the change, the more days had to be canceled. In Sweden there was another difficulty, as the calendar researcher Heinrich Hemme from the Aachen University of Applied Sciences emphasizes: "Since several days had to be skipped when changing the calendar system, many people feared their lifetime would be stolen." Sweden therefore decided to make a cautious transition from the Julian to the Gregorian calendar valid up to now.

One day ahead, two leap days to compensate

From 1700 to 1740, all eleven leap days should be canceled in Sweden, i.e. the 29th February in each case should simply be deleted. The problem with this: the Great Northern War, which was to last until 1721, broke out as early as March. Due to the turmoil of the war, the failure of February 29th was forgotten in 1704 and 1708. 1711 ordered Charles XII. - for the sake of the hoped-for simplicity - the return to the Julian calendar. However, they were now one day ahead of this, so that in 1712 not just one but two leap days had to be inserted. The result: February 30th.

For a long time, however, the Julian annual planning was not adhered to: In 1753, King Adolf Friedrich finally introduced the Gregorian calendar - this time in a leap from February 17th to March 1st.

St. Humorius and Banking

February 30th has not yet been completely shelved. With the "commercial" interest calculation, each month is set at 30 days. For example, if a credit period runs from January 26th to March 2nd, the interest days are calculated as follows: January (30-26) + February (30) + March (2) = 36 interest days. In the artistic field, on the other hand, the Baroque poet Andreas Gryphius emphasized the lack of consequences of a marriage contract in his work "Horribilicribrifax Teutsch" by dating it to February 30, 1648. And the strange date also brought on a joke saint of his own: the holy Humorius.

Julian & Gregorian calendars

The Julian calendar was introduced by the Roman ruler Julius Caesar 45 BC. It divided the year into 365 days, with a day added to the month of February every fourth year (leap year). An average year was 365.25 days long - almost eleven minutes longer than the earth actually needs to go around the sun once. Over the years the minutes added up, after around 128 years the difference was a whole day.

In 1582 the difference between the calendar and the solar year was ten days, which is why Pope Gregory XIII. decided to delete this. He also had the leap year regulation refined. In order to make up for the quarter days, they are always combined into one day in the Gregorian calendar (February 29). However: Every year divisible by four is a leap year, unless the year is divisible by 100. And: every year divisible by 400 also contains a February 29, which is why there was a long February in 2000 and not in 1900.