There’s only a February 29th every four years, which explains why 2024 is a leap year. 

In Spanish, a leap year is called un año bisiesto. You can also refer to a leap day as un día bisiesto.

The word bisiesto originates from the Latin bis sextus dies ante calendas martii (sixth day before the month of March). 

This corresponded to a day between February 23d and 24th brought in by Roman general Julius Caesar in 49BC after coming across a more accurate calendar in Egypt as a means of synchronising the calendar with the solar year. 

#PalabraDelDía | bisiesto

Recuerden que «bisiesto» viene del latín «bisextus» (de «bis» ‘dos veces’ y «sextus» ‘sexto’), término usado porque antiguamente el día que se repetía era el sexto antes de las calendas (o primer día) de marzo. pic.twitter.com/1zK0OPRXS3

— RAE (@RAEinforma) February 29, 2024

This Roman calendar meant to ensure seasonal accuracy was later perfected by Pope Gregory XIII in 1582 – hence the name Gregorian calendar – which still stands today.

The simple reason why leap years play a pivotal role in matching our calendar with the Earth’s orbit around the sun is that it takes 365.24 days for the planet to complete one revolution around the sun, so every 365-day year is a quarter of a day short of the complete orbit.

Generally speaking, Spain considers the leap year as a whole, and the itself day, to bring bad luck.

A few Spanish proverbs sum it up:

Año bisiesto, año siniestro – leap year, sinister year

Año bisiesto y año de pares, año de azares – leap year and even year, random year

Año bisiesto, ni casa, ni viña, ni huerto, ni puerto – Leap year, no home, nor vineyard, nor orchard, nor port.

The chances of being born on a leap day are 1 in 1,461. 

Funnily enough, Spanish Prime Minister Pedro Sánchez is the most famous Spaniard to be born on February 29th, which means that today he actually turns 13 (okay, he’s really 52).

Examples:

El 2024 es año bisiesto, lo cual quiere decir que habrá 366 días en el año.

2024 is a leap year, which means that there will 366 days in the year. 

Cumplir años el día 29 de febrero es una putada, sólo lo puedes celebrar oficialmente cada cuatro años. 

Having your birthday on February 29th is a real shame, you can only officially celebrate it every four years.

La Tierra tarda 365 días, 5 horas, 46 minutos y 48 segundos en dar una vuelta completa al Sol, lo cual explica porque existen los años bisiestos.

Planet Earth takes 365 days, 5 hours, 46 minutes and 48 seconds to complete orbit the sun, which explains why leap years exist.